Resource Library: Multimedia/Resource Library: Multimedia.iso/hypertxt/msdos/zoomschi/schisto.stk

Text File | 1992-10-04 | 244.4 KB | 5,716 lines

@language[English]
@Summary[Schistosomiasis Teaching Programme]
@Chapter[Introduction]
@Slide[WORMPAIR-PCX-]

@Window[This chapter will give you some basic information
regarding schistosomiasis, its epidemiology and its
life-cycle.                                         ]

@Slide[Intro1-Text-]
@Yellow[1. INTRODUCTION]

Schistosomiasis is currently endemic in 76 countries around the world.
It is estimated that more than 200 million persons residing in urban,
rural and agricultural areas are infected among 600 million persons
who are exposed to infection.

These 600 million people are exposed to infection because of poverty,
ignorance, poor housing, inadequate domestic water supply, substandard
hygienic practices, and the availability of few, if any, sanitary facilities.

@Slide[Intro2-Text-Treatment-Snails-Environment-Health Education-Safe water-+-
Sanitation-]




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 ║         @Yellow[Transmission of schistosomiasis can be stopped by:]            ║
 ╚═══════════════════════════════════════════════════════════════════════╝

@Delay[500]            1)    Treatment of infected persons
@Delay[500]            2)    Elimination of snails
@Delay[500]            3)    Environmental management
@Delay[500]            4)    Health education/change in behaviour
@Delay[500]            5)    Provision of safe water supply/sanitation

@Slide[Intro3-Text-Parasitology-Transimission-Data analysis-]




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 ║@Yellow[ This computer programme has been designed to accomplish the following] ║
 ║@Yellow[ objectives:]                                                           ║
 ╚═══════════════════════════════════════════════════════════════════════╝

@Delay[500]      1)    Introduce you to the parasitology of @LightCyan[Schistosoma],

@Delay[500]      2)    Help you understand the role of people in the
            transmission of schistosomiasis, and

@Delay[500]      3)    Prepare you to meaningfully analyze the data from
            schistosomiasis control programmes.

@Slide[Intro4-Text-S. japonicum-S. mansoni-S. haematobium-S. intercalatum-]
@Yellow[2.  Current epidemiological situation]

Different species of @lightcyan[Schistosoma] are endemic in different places around
the world.  In some areas of the world, only one type of schistosomiasis
is present.  In other places, two or more types of schistosomiasis may
be present.

The distribution of schistosomiasis is neither uniform nor contiguous as
can be seen in the following maps.  However, one of the limiting factors
in its distribution is the presence of fresh water.

The geographical distribution is wide - ranging from China; the Philippines
and Indonesia,  @lightcyan[Schistosoma japonicum], through the Arabian Peninsula and
nearby states, the Sudan and the Nile valley and delta, numerous countries
of the north African littoral and the whole of sub-Saharan Africa,
@lightcyan[S. mansoni] and @lightcyan[S. haematobium], to the New World - Brazil; Suriname;
Venezuela and certain Caribbean islands, @lightcyan[S. mansoni]. As agricultural,
hydroelectric and other water resources development projects expand in the
endemic countries, transmission of schistosomiasis is spreading and the
degree of transmission is intensified.

@Slide[Intro5-Text-S. haematobium-S. intercalatum-Urinary schistosomiasis-+-
Rectal schistosomiasis-]


@lightcyan[Schistosoma haematobium], the cause of urinary schistosomiasis, is endemic
in 55 countries of the Eastern Mediterranean and African regions.

@lightcyan[Schistosoma intercalatum], the cause of rectal schistosomiasis, is increa-
singly recognized in Central Africa.  It is now endemic in Cameroon,
Central African Republic, Chad, Congo, Equatorial Guinea, Gabon,
Sao Tome and Principe, and Zaire.

@Slide[Quiz1-quiz-76-]


How many countries in the world are endemic with schistosomiasis? ___




@Slide[Mapsh-PCX-S. haematobium-S. japonicum-S. mansoni-]

@Slide[Intro6-Text-S. mansoni-S. japonicum-]


@lightcyan[Schistosoma mansoni], the cause of intestinal schistosomiasis, is endemic
in 52 countries of the Region of the @lightgreen[Americas], @lightgreen[Africa] and the @lightgreen[Eastern]
@lightgreen[Mediterranean Regions].

@lightcyan[Schistosoma japonicum], which also causes intestinal schistosomiasis,
is endemic in countries of the @lightgreen[Western Pacific Region].

In six countries, all three species of @lightcyan[Schistosoma] are endemic.

Both @lightcyan[S. mansoni] and @lightcyan[S. haematobium] are endemic in 41 countries of @lightgreen[Africa]
or the @lightgreen[Eastern Mediterranean Region].

@Slide[mapsm-PCX-S. mansoni-S. intercalatum-]

@Slide[sickboy-PCX-Control programme-Liver-Spleen-Esophageal varices-Treatment-]

@window[The objective of schistosomiasis control programme is to reduce
the severe disease caused by various types of schistosomiasis.
As seen in this picture, this young boy has severe disease of
the liver and spleen due to schistosome mansoni.  This form of
the disease is called hepatosplenic schistosomiasis and is
associated with bleeding from esophageal varices.  Even at this
stage, treatment can be beneficial.]

@Slide[Intro7-Text-Intestine-Bladder-Rectum-Life cycle 
-Venous vessel-Parasitology-]
@Yellow[3.  LIFE-CYCLE OF SCHISTOSOMA]

The life-cycle of Schistosoma has two phases.  The sexual phase involves
adult male and female worms which develop in the venous blood vessels of
the intestine (@lightcyan[S. mansoni] and @lightcyan[S. japonicum]), the bladder (S. haematobium),
or the rectum (@lightcyan[S. intercalatum]).  The eggs are passed from the human body
through urine or faeces.

@lightcyan[S. mansoni], @lightcyan[S. haematobium] and @lightcyan[S. intercalatum] all develop in aquatic
snails, snails that live entirely in the water.  @lightcyan[S. japonicum] develops
in amphibious snails, snails that can live on land as well as in the water.

When excreted eggs come in contact with water, miracidia hatch out of the
egg.  Miracidia are ciliated (covered with fine hair) organisms.  The
movement of the cilia propels the miracidium.  In order to develop further
it must come into contact with the proper fresh water snail within a
maximum of 72 hours after hatching.

@Slide[miracid-PCX-Parasitology-]

@Window[This is a picture of a miracidium.
The color was added to enhance the
picture and is not true in the real
organism.  Notice the cilia around
the body of the miricidium.]

@Slide[Intro8-Text-Miracidium 
-Cercariae 
-Mammalian host-Sexual phase-Adult worm 
-+-
Snail 
-Parasitology-Cercariae-]

Inside of the snail, the miracidium is transformed sequentially into a
sporocyst, daughter sporocysts and then cercariae.  One miracidium
developes into thousands of cercariae.

Cercaria will emerge from the snail host after 4-7 weeks.  Cercaria are
microscopic organisms with a tail used for swimming.  Cercaria must come
in contact with a suitable mammalian host within 48 hours or they will die.
If a suitable mammalian host is found, cercaria will penetrate the skin of
the host and begin the sexual phase of the life cycle.

Each cercariae after entering the host's body, develops into a single
adult worm, either male or female.  All cercariae from the same sporocysts
develops into adults of same sex.

@lightgreen[The time required for the worms to mature, to mate and to start to lay eggs]
@lightgreen[is between 30 and 45 days.]


@Slide[cercaria-PCX-Parasitology-]

@Window[This is a piture of a cercaria.
There are two parts, the head and the
tail.  The tail is used to propel the
organism through water.]


@Slide[Intro9-Text-]

This training course will introduce you to the parasites which cause
different form of human schistosomiasis and will assist you in understanding
the role of people in all aspects of schistosomiasis.



@SUBSLIDE[NothingMsg-Text-]





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║            This key word/index choice has not yet been entered.           ║
║   Please make another selection after going back using the @yellow[F2] or @yellow[F4] key.  ║
╚═══════════════════════════════════════════════════════════════════════════╝


@chapter[Epidemiology]
@Slide[EpiIntro-PCX-]

@window[This chapter will describe and explain basic epidemiological
concepts and terminology.  At the end of this chapter you will
know the meanings of various terminology, ask meaningful questions
to answer problems in control and be able to calculate basic
epidemiological data.]

@Slide[EpiIntro1-Text-]
@Yellow[1.  Introduction]

Although there are many principles which are important in analysis of
epidemiological data, one of the most important is to develop a hypothesis
statement for each analysis.  This statement will then guide you in
performing proper analysis.

For example, even the census data should be viewed with a hypothesis:
@LightCyan[The proportion of the population greater than 20 years of age is]
@LightCyan[smaller than that of the population less than 20 years of age.]

The basis for this hypothesis statement is that in most developing countries
the high birth rate results in the majority of the population being less
than 20 years of age.  If the data shows otherwise, then other hypothesis
can be explored.

Routine completion of census tables or age-sex distribution should be
avoided.  Think about the questions you want to answer before entering the
data.

@Slide[Epi2-TEXT-Control programme-Rates-Census-Survey-]
@Yellow[2.  Population]

In order to carry out any control programme, you must have an understanding
of the people you are trying to reach.  The single most basic and important
information you need is the size of the population.

You need this information to carry out the surveys, and to calculate various
rates important for successfully carrying out the control programme.

Within a defined geographical area, the size of the resident population
can be determined accurately by a house to house census. In many countries
the census data is very accurate and can be used in control programmes or
for epidemiological surveys.

@Slide[Epi3-Text-School-Survey-Census-]

If recent census data is available, then you can use this information for
the size of the population rather than conducting a separate survey.

The size of the population will be used in the calculation of epidemio-
logical data.  Most often, the population figures will be used as the
denominator when calculating rates.

If the control programme is directed to a school, then every student
attending that school must be recorded.

If a recent census of community is available, then you can use this
information for the size of population rather than conducting a separate
census survey.

@Slide[Censform-PCX-]

@Window[The design of the census recording form requires that
you decide what information will be needed in the control
programme or epidemiological study.]

@Window[A census recording was developed for use by the
schistosomiasis research and control service of
the Ministry of Health of the Philippines.]

@Window[All data is recorded as numeric codes.

The codes appearing before the name on the
card permits a unique identification number
for each person in the house and allows for
new persons to be added later.]

@Slide[Epi4-Text-]
@yellow[3.  Rates]

A @lightgreen[rate] is a ratio of two numbers.  In other words, a rate is a fraction,
or a proportion.  In epidemiology, one is interested in the fraction of a
proportion of people who are infected, cured, treated, etc.  In order to
calculate these numbers, you need to have a numerator and a denominator.

For example, let us look at the data from a survey of 1981 in Zanzibar.
There were 3450 people registered in the house to house census, but only
2668 were examined.  The rate of coverage would be:

@delay[500]                 2668  -  Total number of people examined
@delay[500]              ÷  3450  -  Total number of people
@delay[500]                 ----
                 .77  -  Fraction of people examined
@Delay[500]                x 100 [%] To calculate the percentage
@delay[500]                 ----
                  77 %   Coverage rate

@window[The data is from 1982 survey.  Reference WHO document
WHO/SCHISTO/85.81 Rev. 1.  "Statistical Methods Applicable
to Schistosomiasis Control Programme".]

@Slide[Epi5-Text-]
@Yellow[4.  Prevalence]

The term @lightgreen[prevalence] usually refers to the proportion of the population
infected with schistosomiasis, i.e. the proportion of individuals with
schistosome eggs in their urine or faeces.

For example, let us go back to the data from Zanzibar.  In 1981, out of
2668 persons examined, 1317 persons were found to be infected with
S. haematobium.  The prevalence would be:

@delay[500]                    1317    -  Number infected
@delay[500]                  ÷ 2668    -  Number examined
@delay[500]                    ----
                    .49    -  Fraction of people infected
@Delay[500]                   x 100 [%]   To calculate the percentage
@delay[500]                    ----
                     49 %  -  Prevalence of S. haematobium in
                              this population
@delay[500]
@Slide[Epi6-Text-Treatment-Coverage-Prevalence-Rates-Rates/Specific-]
@yellow[4.1   Sex-specific prevalence rates]

The two terms used previously, @lightgreen[coverage] and @lightgreen[prevalence], can be used to
describe a group of people.  However, in a control programme, you are usually
interested in a more detailed picture of what is going on.  Therefore, in
order to understand how the disease and the treatment is affecting the
population, you may want to look at the rates based on sex.

@Slide[Epi7-Text-]

The following calculation is based on the data from Zanzibar. The population
is divided into two groups, males and females, and rates are calculated for
each group separately.

                            2668 Total Examined


@lightcyan[            Male                                 Female]

@delay[500]   719  - No. of infected males           598 - No. of infected females
@delay[500]÷ 1343  - Total no. of males examined  ÷ 1325 - Total no. of females examined
@delay[500] -----                                  -----
  .54   - Fraction infected              .45  - Fraction infected
@delay[500]x 100%  - To get percentage            x 100% - To get percentage
@delay[500] -----                                  -----
   54%  - Prevalence in male              45% - Prevalence in female

@Slide[Epi8-Text-Age specific rates-]

As you can see from the calculation on the previous screen, the rates for
male and female are very different.  By dividing the population into
different groups based on some characteristic, one can get a better
understanding of how the disease is affecting the different sub-groups
within the population.

In epidemiology, such grouping is called @lightgreen[stratification].  You can stratify
by sex, as you have just seen, by age, as you will soon see, or by any other
characteristics that may represent different sub-groups within the population.

However, one has to be careful since stratification may hide some important
information.

@Slide[Epi9-Text-]



                P    100 │
                r        │
                v        │
                a        │ @LightCyan[  54%]
                l        │@LightCyan[ ▄▄▄▄▄▄▄] @LightMagenta[     45%]     @LightGreen[   49%  ]
                e     50 │@LightCyan[ ███████]              @LightGreen[ ▄▄▄▄▄▄▄]
                n        │@LightCyan[ ███████] @LightMagenta[   ███████]   @LightGreen[ ███████]
                c        │@LightCyan[ ███████] @LightMagenta[   ███████]   @LightGreen[ ███████]
                e        │@LightCyan[ ███████] @LightMagenta[   ███████]   @LightGreen[ ███████]
               (%)       │@LightCyan[ ███████] @LightMagenta[   ███████]   @LightGreen[ ███████]
                       0 └────────────────────────────────
                          @LightCyan[   Male ] @LightMagenta[    Female]   @LightGreen[ Overall]


       Sex specific prevalence rates.  From 1982 survey, Zanzibar.
       Reference WHO document WHO/SCHISTO/85.81 Rev. 1.  "Statistical
       Methods Applicable to Schistosomiasis Control Programme".
@Window[One way of describing this difference is by presenting
the data graphically.  As people say, sometimes a
picture is worth a thousand words.  This is especially
true for public presentations and teaching. ]
@Window[This is a graph of sex-specific prevalence rates.
The three bars represent prevalence rates for
male, female and overall.]
@Window[As you can see, the overall prevalence rate is very different
than the sex-specific prevalence rates.  And also, the male
prevalence rate is higher than the female prevalence rate.  This
tells us that in this population the males are more likely to be
infected than the females.]
@Window[If you were to state that the prevalence rate for this population
was 49%, although you would be correct, you would miss the fact that
males have over 10% greater chance of being infected than the females.]
@Window[Therefore, it is very important to stratify the data by sex.]

@Slide[Epi10-Text-Rates/Specific-]
@yellow[5.  Age specific rates]

Let's take prevalence rates a step further.  You know why it is important
to calculate sex-specific prevalence rates.  In addition, with most
diseases, the age of the person can often determine whether they are
infected or not.  The next step, therefore, would be to look at the
different age groups and calculate age-specific prevalence rates.

In the 1981 survey, 1343 males and 1325 females were examined.  The
examination had revealed that 719 (54% of 1343) males and 598 (36% of 1325)
females were infected with S. haematobium.

Based on one's knowledge of water contact patterns, it is useful to
determine if children have higher rate of infection than the adults.

We need to calculate the age-specific rates to confirm our hypothesis.

@Slide[Epi11-Text-]

@yellow[                     Zanzibar, 1982 : Male population]

┌──────┬──────┬──────┬─────┬────────────────────────────────────┬───────────┐
│ Age  │ No of│ No.  │ No. │   No of eggs per 10 ml. of urine   │ Preval (%)│
│      │ Pers │ Exam │ Pos │ 0  │1-9│10-19│20-29│30-39│40-49│50+│ 50+ │Total│
├──────┼──────┼──────┼─────┼────┼───┼─────┼─────┼─────┼─────┼───┼─────┼─────┤
│ 0-4  │  229 │  185 │  39 │146 │ 26│   1 │   1 │   2 │  2  │  7│  3.8│ 21. │
│ 5-9  │  444 │  316 │ 206 │110 │ 45│  15 │  13 │  11 │  5  │117│ 37.0│ 65. │
│10-14 │  351 │  295 │ 219 │ 76 │ 59│  18 │  13 │  10 │  6  │113│ 38.3│ 74. │
│15-24 │  252 │  185 │  95 │ 90 │ 40│   6 │   8 │   5 │  2  │ 34│ 18.4│ 51. │
│25-44 │  280 │  190 │  82 │108 │ 50│   7 │   4 │   4 │  1  │ 16│  8.4│ 43. │
│ 45+  │  228 │  172 │  78 │ 94 │ 38│  10 │   6 │   6 │  0  │ 18│ 10.5│ 45. │
│Total │ 1784 │ 1343 │ 719 │624 │258│  57 │  45 │  38 │ 16  │308│ 22.7│ 53. │
└──────┴──────┴──────┴─────┴────┴───┴─────┴─────┴─────┴─────┴───┴─────┴─────┘


*From 1982 survey, Zanzibar. Reference WHO document WHO/SCHISTO/85.81 Rev.1.
"Statistical Methods Applicable to Schistosomiasis Control Programme".

@window[We will limit the exercise to male population.
However, the same procedure can be applied to
female population as well.]
@window[We notice from this table that the population
has been divided into six age groups. These are standard
epidemiological classifications and permit comparisons
with data from other countries.]
@window[We can see that the prevalence rates for the
six age groups are very different.  The 10-to-14
years-old age group has more than three times the
infection of the 0-to-4 years-old age group.]
@window[It is, therefore, very useful and important to
break down the numbers into different age groups.]

@Slide[Epi12-Text-Morbidity-Egg count-Diagnosis-]
@yellow[6.  Intensity of infection]

Next, we need to examine the issue of the @lightgreen[intensity of infection].
Schistosomiasis infections, like many other infections, vary in severity
between age groups, sexes and even individuals among the same age and sex.
If only prevalence data is available, it is like looking at a flat map.
Data on intensity shows the variations in height, making the picture three
dimensional, and therefore more informative.  Indication of group of heavily
infected persons is a warning signal of frequent contact with a transmission
site.

It is, therefore, important for the schistosomiasis control programme
manager to be aware of the concept of intensity of infection.

Intensity of infection is sometimes used as a measure for the @lightgreen[morbidity],
or to determine how sick a person is.  Higher the intensity of infection,
sicker the person.  In a schistosomiasis control programme, there are
several ways to measure the intensity of infection.

The method that we will describe here uses direct parasitological technique,
the egg count.  More on this technique can be found under the chapter
heading @lightgreen[Diagnosis].

@Slide[Epi13-Text-]

@yellow[                     Zanzibar, 1982 : Male population]

┌──────┬──────┬──────┬─────┬────────────────────────────────────┬───────────┐
│ Age  │ No of│ No.  │ No. │   No of eggs per 10 ml. of urine   │ Preval (%)│
│      │ Pers │ Exam │ Pos │ 0  │1-9│10-19│20-29│30-39│40-49│50+│ 50+ │Total│
├──────┼──────┼──────┼─────┼────┼───┼─────┼─────┼─────┼─────┼───┼─────┼─────┤
│ 0-4  │  229 │  185 │  39 │146 │ 26│   1 │   1 │   2 │  2  │  7│  3.8│ 21. │
│ 5-9  │  444 │  316 │ 206 │110 │ 45│  15 │  13 │  11 │  5  │117│ 37.0│ 65. │
│10-14 │  351 │  295 │ 219 │ 76 │ 59│  18 │  13 │  10 │  6  │113│ 38.3│ 74. │
│15-24 │  252 │  185 │  95 │ 90 │ 40│   6 │   8 │   5 │  2  │ 34│ 18.4│ 51. │
│25-44 │  280 │  190 │  82 │108 │ 50│   7 │   4 │   4 │  1  │ 16│  8.4│ 43. │
│ 45+  │  228 │  172 │  78 │ 94 │ 38│  10 │   6 │   6 │  0  │ 18│ 10.5│ 45. │
│Total │ 1784 │ 1343 │ 719 │624 │258│  57 │  45 │  38 │ 16  │308│ 22.7│ 53. │
└──────┴──────┴──────┴─────┴────┴───┴─────┴─────┴─────┴─────┴───┴─────┴─────┘

*From 1982 survey, Zanzibar. Reference WHO document WHO/SCHISTO/85.81 Rev.1.
"Statistical Methods Applicable to Schistosomiasis Control Programme".

@window[Referring back to the table that we used to
calculate age-specific prevalence rates, we can
also see the columns used for the intensity of infection.]
@window[These columns describe how many Schistosoma eggs
were observed under the microscope.  The range used
for S. haematobium is between 0 eggs, which is negative,
to 50+ eggs which is heavily infected.  The egg count is
based on urine filtration technique using 10 ml of urine.]
@window[Sometimes we are only interested in heavily infected
individuals since usually they are also the ones that
are most ill.  This is the reason why there is often
a separate prevalence rate column for 50+ egg count
individuals.]

@SubSlide[TClustEMM-Text-]
@Yellow[TEMPORAL CLUSTERING]

@Yellow[Ederer, Myers, and Mantel approach]

Ederer, Myers, and Mantel developed a test for temporal clustering
using a cell-occupancy approach. They divided the time period into k
disjoint subintervals. Under the null hypothesis of no clustering, the
n cases are randomly distributed among the subintervals (i.e., are
multinomially distributed). The test statistic m is the maximum number of
cases occurring in a subinterval. lf the health event is rare and of
unknown etiology, m is summed over several locations and time periods.
The sum is tested by using a single degree of freedom chi-square test.
Ederer, Myers, and Mantel and Mantel, Kryscio, and Myers provide
tables of the exact null distribution of m for selected values of k and n.

@SubSlide[TClustST1-Text-]
@Yellow[Scan Test]

Naus proposed a test of temporal clustering that is known as the scan test.
The test statistic, the maximum number of cases observed in an interval of
length t, is found by "scanning" all intervals of length t in the time
period (resulting in overlapping intervals). ln certain cases, this
approach is intuitively more appealing than the disjoint interval approach
of Ederer, Myers, and Mantel, but more complicated mathematically. However,
situations exist for which the disjoint interval approach is the more
satisfactory choice. Statistical significance of the scan test is assessed
by using tables of p-values calculated by Naus and Wallenstein for selected
interval lengths, time lengths, and sample sizes. Unfortunately, the
computations necessary to obtain other exact p-values for the scan statistic
are complex and often not feasible. However, Knox and Lancashire have
derived a set of relatively simple formulas for an approximation to the
exact p-value. (continued)

@SubSlide[TClustST2-Text-]
(Scan test continued)

Naus compared the power of the scan test with that of the Ederer, Myers,
and Mantel test and concluded that if the scanning interval is small and
the data are continuous over the interval, the scan test is the more
powerful of the two. Weinstock proposed a generalization of the scan test
that adjusts for changes in the population at risk.

@SubSlide[TClustBEM-Text-]
@Yellow[Bailar, Eisenberg, and Mantel Test of Temporal Clustering]

Bailar, Eisenberg, and Mantel suggested a test of temporal clustering based
on the number of pairs of cases in a given area that occur within a
specified length of time d of each other. The numbers of close pairs
occurring in q areas are summed. The teSt statistic is assumed to be
approximately normally distributed.

@SubSlide[TClustLT-Text-]
@Yellow[Larsen Test]

Larsen, Holmes, and Heath developed a rank order procedure for detecting
temporal clustering. The time period is divided into disjoint subintervals
that are numbered sequentially (i.e., ranked). The test statistic K is the
sum of absolute differences between the rank of the subinterval in which a
case occurred and the median subinterval rank. Small values of K indicate
unimodal clustering. Generally, the K statistics for multiple geographic
areas are summed. The resulting statistic is asymptotically normal with
simple mean and variance. This test is sensitive only to unimodal
clustering; it cannot distinguish multiple clustering from randomness.

@SubSlide[TClustTCI-Text-]
@Yellow[Tango Clustering lndex]

Tango developed a test of temporal clustering based on the distribution of
counts in disjoint equal time intervals. The test is useful when the data
are grouped. The test statistic (cluster index) is a quadratic form
involving the relative frequencies in each interval and a measure of
distance between intervals. The clustering index obtains a maximum value
of 1 when all cases occur in the same interval. Although the statistic is
easy to calculate, the asymptotic distribution using Tango's formula is
not. However, Tango will provide upon request an algorithm written in
BASIC to obtain the asymptotic distribution.

Whittemore and Keller showed that the distribution of Tango's index is
asymptotically normal with simple mean and variance.

@SubSlide[SClustGCR-Text-]
@Yellow[SPATIAL CLUSTERING]

@Yellow[Geary Contiguity Ratio]

Geary developed a test of spatial clustering that assesses whether rates
for adjacent areas are more similar than would be expected if they were
randomly distributed among the geographic areas. The test statistic, the
contiguity ratio, is the ratio of the sum of mean squared differences
between rates for pairs of adjacent areas to the weighted sum of mean
squared differences between rates for all pairs of areas, lf the rates are
geographically distributed at random, the contiguity ratio is close to one;
otherwise, it is less than one. Geary derived an expression for the
approximate variance of the ratio. If the number of areas is not too small,
the ratio is asymptotically normally distributed. Hechtor and Borhan provide
another computational formula for the statistic.

@SubSlide[SClustOAA-Text-]
@Yellow[Ohno, Aoki, and Aoki Test]

Ohno, Aoki, and Aoki and Ohno and Aoki developed a simple test for spatial
clustering that uses rates for geographic areas (e.g., census tracts,
counties, or states) rather than data for individual cases. The test
assesses whether the rates in adjacent areas are more similar than would be
expected under the null hypothesis of no clustering.

For this test, the rate for each area is classified into one of n
categories, and each pair of adjacent areas is identified. The test
statistic is the number of adjacent concordant pairs -i.e., the number of
pairs of areas that are adjacent and have rates in the same category. An
overall clustering measure (summed across all categories) can be obtained
as well as category-specific clustering measures. The observed number of
adjacent concordant pairs is compared with the expected number by using a
chi-square test. Ohno, Aoki, and Aoki provide a simple formula for
calculating the expected number of pairs.

@SubSlide[SClustGT-Text-]
@Yellow[Grimson Test]

Grimson, Wang, and Johnson proposed a test of spatial clustering for use
in detecting clusters of geographic areas designated as high risk. The null
hypothesis is that high-risk areas are randomly distributed within a larger
area and do not cluster.

Given n high-risk areas, the test statistic is the number of pairs of high-
risk areas that are adjacent to each other. This statistic is equivalent to
the category-specific statistic from Ohno, Aoki, and Aoki. Grimson et al.
recommended using a simple Monte Carlo simulation to obtain p-values for
the test statistic.

@SubSlide[SClustWT-Text]
@Yellow[Whittemore Test]

Whittemore, Friend, Brown, and Holly developed a test for spatial clustering
across geographic areas that adjusts for different distributions of
population subgroups across the region. Thus, the test requires population
data, The test statistic is the mean distance between all pairs of cases,
and can be expressed as a generalization of Tango's clustering index -i.e.
a quadratic form involving relative frequencies from subgroups and a matrix
of distances between pairs of areas. The statistic is asymptotically normal
(mean and variance derived), and the test has good power when disease rates
for all subgroups are elevated in the same areas. Power is poor when areas
with elevated rates vary for subgroups. The test also has poor power when
clusters occur in more than one area. The test can be adapted to detect
temporal ciustering when the distance matrix represents distances between
pairs of time intervals.

@SubSlide[SClustCET-Text-]
@Yellow[Cuzick and Edwards Test]

Cuzick and Edwards proposed a test for spatial clustering that applies to
populations with non-uniform population density. The test involves drawing
a set of controls from the population and combining them with the cases.
Cuzick and Edwards propose two nearest-neighbor tests. The statistic for the
first test is the number of persons in the case group whose nearest neighbor
also is in the case group. The second test statistic is the sum of the
number of cases among the K nearest neighbors for each person who is in the
case group. This second test will be more powerful when a few large clusters
exist, whereas the first test is more powerful when many small clusters are
involved. Cuzick and Edwards provide formulas for the mean and variance and
establish asymptotic normality for the test statistics.

@SubSlide[STClustCOA-Text-]
@Yellow[SPATIAL AND TEMPORAL CLUSTERING]

@Yellow[Pinkel and Nefzger Cell Occupancy Approach]

ln 1959, Pinkel and Nefzger proposed a cell occupancy approach to test for
spatial-temporal clustering. Assuming that r cases are randomly allocated
to m space-time cells, these investigators developed an exact test for
determining the probability of observing k "close" cases (i.e., cases
occurring within a specified distance and length of time of each other).

For this test, the study area and time period are divided into space-time
cells based on the space and time distances used to define closeness. The
test is sensitive not only to space-time clustering but also to spatial
clustering or temporal clustering alone, a property that is not desirable.

@SubSlide[STClustKnx-text-]
@Yellow[Knox 2 x 2 Contingency Table Test]

Knox developed a space-time clustering test that involves dichotomizing the
spatial and temporal dimensions. A 2 x 2 contingency table is formed by
classifying the n(n-1 )/2 pairs of cases as close in space and time, close
in space only, close in time only, or close in neither space nor time.

The test statistic X, the observed number of pairs close in both space and
time, is assumed to be approximately Poisson (since although pairs are
dependent, X is small compared with the total number of pairs).

Barton and David concluded that, although use of the Poisson approximation
is appropriate in some situations, in general it could yield misleading
results. Mantel outlined methodology for obtaining the exact permutational
distribution of X.

@SubSlide[STClustPLA1-Text-]
@Yellow[Barton and David Points-on-a-Line Approach]

Barton, David, and Herrington and David and Barton adapted an earlier test
for use in detecting space-time interaction. The test, analogous to analysis
of variance, involves the ratio of within-group variance to overall
variance. Pairs of cases separated in time by less than a specified length
of time are formed into time clusters (i.e. treatment groups).

The test statistic Q is the ratio of the average squared geographic distance
between pairs of cases within clusters to the average squared distance
between all pairs of cases. Under the null hypothesis of no space-time
interaction, one would expect this ratio to be 1. When clustering is
present, Q is smaller than 1. To assess significance, David and Barton
suggested using a randomization test to determine the exact distribution of
Q. Since calculation of the exact distribution often is not feasible,
Barton and David suggested using a beta approximation when the number of
cases is small and a normal approximation when the number of cases is large.
When the number of clusters is large, Q is approximately normally
distributed; otherwise, an F approximation is more appropriate.
(continued)

@SubSlide[STClustPLA2-Text-]
(Barton and David Points-on-a-Line Approach continued)

An advantage of Barton and David's test is that actual distances are used,
and the only arbitrariness is in the selection of the critical time point.
A disadvantage of the test is that the small distances, which are of most
interest, have less influence on the statistic than do the large distances.
ln fact, the large distances may so dominate the statistic that they mask
any clustering.

@SubSlide[STClustMGRA1-Text-]
@Yellow[Mantel Generalized Regression Approach]

Mantel developed a "generalized regression" approach to the detection of
clustering in space and time. The test statistic Z is the sum over all
pairs of cases of a function of the distance between two cases multiplied
by a function of the time between two cases. Knox's test can be derived as
a special case of Mantel's test. Mantel recommended using reciprocal
transformations of the distances to increase the influence of close
distances and decrease the influence of long distances. Mantel and
Siemiatycki concluded that the test has low power if no transformation is
made.

A constant must be added to the distances before making the reciprocal
transformation because of the possibility of very small or zero time and/or
space distances. Unfortunately, the constants chosen influence the value of
the test statistic and the outcome of the test of significance if the normal
approximation is used. Mantel suggested that, for best results, the
constants be close to the expected distances between close pairs. Glass,
Mantel, Guns, and Spears and Siemiatycki found that as the size of the
constants increases, the test statistic tends to decrease.
(continued)

@SubSlide[STClustMGRA2-Text-]
(Mantel Generalized Regression Approach continued)

A test of statistical significance is obtained by obtaining the exact
randomization distribution of Z, by using Monte Carlo simulation to obtain
an approximation to the distribution of Z, or by assuming that Z is as,
asimptotically normally distributed (Mantel derived expressions for the
measured variance). Klauber and Siemiatycki found the distribution of Z to
be highly skewed and showed that although the use of the normal
approximation is appropriate when Z is highly significant or nonsignificant,
its use is inappropriate when Z has borderline significance.

One asset of Mantel's test is that actual space and time distance are used,
thus avoiding arbitrary cutpoints and loss of information. Another advantage
to this approach is its applicability to two or more samples.

@SubSlide[STClustPSE-Text-]
@Yellow[Pike and Smith Extension to Knox Test]

Pike and Smith extended Knox's test to diseases with long latent periods
by defining a geographic area and period of time of infectivity and
susceptibility. Pairs of cases are considered close in space if their
geographic areas of infectivity and susceptibility overlap, and close in
time if their periods of infectivity and susceptibility overlap. The test
statistic is the number of pairs close in both space and time.

@SubSlide[STClustLRT-Text-]
@Yellow[Lloyd and Roberts Test]

Lloyd and Roberts outlined a test for either spatial or temporal clustering
that Smith and Pike noted in 1974 can be viewed as a special case of Knox's
test. Lloyd and Roberts suggested using the number of pairs among all
possible pairs of cases that are close in time (or in space) as the test
statistic. A test of significance is obtained by calculating the mean number
of close pairs for sets of randomly selected controls and by assuming a
Poisson distribution with this mean. Smith and Pike indicated that the
randomization distribution of the test statistic could be obtained, and they
suggested that matched controls be used in the procedure.

@chapter[Parasitology]
@Slide[ParaIntr-PCX-]

@window[This chapter will explain basic parasitology.
You will learn about the various species of
Schistosoma, and learn about their life-cycle.
You will also learn about the intermediate host,
fresh water snails.]

@Slide[Para2-Text-]
@yellow[1. Introduction]

Parasitology is the study of parasites.  A parasite is an organism whose
life-cycle is maintained within other living organisms.

@lightcyan[Schistosoma] is a parasite whose life-cycle is composed of two hosts: snail
intermediate host and human final host.

Understanding the life-cycle of @lightcyan[Schistosoma] and its relationship with the
hosts is vital in controlling the disease.

@Slide[LifeCycl-PCX-Eggs,47,15,57,18-Miracidium,29,16,38,18-Cercariae,37,10,46,11-+-
Adult worm,61,11,69,15-Snails,13,11,19,16-]

@Window[Here is a graphical representation of the life-cycle of
Schistosoma.  You can find out about each stage of the life-
cycle by choosing the "picture" and pressing Enter.]

@Slide[SnailIH-Text-S.j. snail 
-S.m. snail 
-S.h. snail 
-S.i. snail 
-]
@yellow[2.  Snail intermediate hosts]

The snail intermediate host is an essential link in the life-cycle of the
schistosome parasite.  An adequate knowledge of its taxonomy, genetics,
physiology, distribution, and ecology is necessary if its role in
transmission is to be interpreted correctly.

The shell of a snail is a conical tube, spirally coiled around a central
axis.  The separate coils of the spiral are called whorls.  The whorls are
usually in close contact, each whorl being partially covered by its
successor.

A shell may be either dextral (opening to the right) or sinistral (opening
to the left), when held with the opening facing the observer and the point
held up.

@SubSlide[SJSnail-PCX-S. japonicum-]

@window[S. japonicum is transmitted by the polytypic species of Oncomelania
huepensis.  The oncomelanid shell is small, dextral, conical or sub-
conical with four to eight whorls.  The height varies from 3 mm to 10 mm
and the shell may be smooth, have fine axial growth lines or strong axial
ribs.]

@SubSlide[ShSnail-PCX-S. haematobium-]

@Window[The genus Bulinus contains most of the snail intermediate hosts of
S. haematobium.  The bulinid shell is sinistral and higher than it is wide.
The height varies between 4 mm and 23 mm and there are usually four or
five whorls, but there may be as many as seven.]

@SubSlide[SMSnail-PCX-S. mansoni-]

@Window[The genus Biomphalaria is the snail intermediate hosts of S. mansoni.  The
shell is discoid or lens shaped, forming a disc of variable height with
diameter of between 7 mm and 22 mm.  The number of whorls varies between
3½ and almost 7.]


@Slide[Para4-Text-]
@Yellow[3.  Parasite]

@Yellow[3.1  S. japonicum]

@Yellow[3.1.1  Adult worm - S. japonicum]

@lightcyan[S. japonicum] causes disease similar to that observed for @lightcyan[S. mansoni]
infection.  Population based epidemiological studies have shown no difference
in the severity of disease when the egg excretion of @lightcyan[S. mansoni] and
@lightcyan[S. japonicum] infected person is similar.  Each @lightcyan[S. japonicum] female worm can
produce up to 10 times more eggs per day than an @lightcyan[S. mansoni] adult female
worms.

In areas where @lightcyan[S. japonicum] is endemic the population distribution of
infection seems to be different from that of other forms of schistosomiasis.
Though heavy infections occur in school age children, other age groups may
be equally or more heavily infected. In general, persons with high egg
counts have an enlarged liver or spleen.

@Slide[SjEgg-PCX-]

@Window[The S. japonicum female worm tends to produce eggs in clumps.
Therefore, these clumps of eggs cause more inflammation than the
single S. mansoni egg.

The eggs of S. japonicum have small, rudimentary spines and are
rather round.]


@Slide[Para5-Text-]
@Yellow[3.2  S. haematobium]

The public health importance of @lightcyan[S. haematobium] infection has been recognized
for thousands of years since the times of the Egyptian pharaohs.  The adult
worms reside in the venous blood vessels around the bladder.  Therefore, it
causes disease of the genito-urinary tract.

@lightcyan[S. haematobium] is now endemic in 55 Eastern Mediterranean and African
countries.  However, @lightcyan[S. haematobium] has been eradicated from Portugal,
Sardinia, Cyprus and Israel in this century.  In addition, there are foci
in India.

A large body of data is available from well defined communities where
@lightcyan[S. haematobium] is endemic. Almost without exception, the peak prevalence and
intensity of infection occurs among children who are 10-14 years of age. In
general, 60-70% of all infected persons are between 5-14 years of age and
about 75-80% of all persons with more than 50 eggs per 10 ml urine are in
this age group.

@Slide[Para6-Text-Reagent-Haematuria-Urine-]

In children and adults, levels of haematuria and proteinuria are associated
with increasingly heavy @lightcyan[S. haematobium] infections. Cystoscopic, renographic
and radiological changes of the urinary tract are associated with heavy
infections in children. In several studies, among children with more than
50 @lightcyan[S. haematobium] eggs per 10 ml of urine nearly all (98-100%) have
haematuria detected by chemical reagent strips. Among all infected children,
80% have haematuria. Bloody urine may be visible in 10-20% of infected
children.

@Slide[ShEgg-PCX-]

@Window[The eggs of S. haematobium have a terminal spine and the
deposition/accumulation of eggs is focal.]


@Slide[Para7-Text-]
@Yellow[3.3 S. mansoni]

@lightcyan[S. mansoni] affects the liver, spleen and intestine.  Symptoms are usually
only related to very high levels of egg excretion.  It is assumed that high
egg counts mean that many adult worms are present.

@lightcyan[S. mansoni] is found mainly in sub-Saharan Africa and in South America.

In @lightcyan[S. mansoni] endemic areas a small proportion (about 6%) of the infected
population usually excretes at least 50% of the total number of eggs
contaminating the environment. Most of these heavily infected persons are
between 10 and 14 years of age. A high proportion of children with
@lightcyan[S. mansoni] egg counts of over 100 eggs per gram of faeces have enlarged
livers and spleens.

@Slide[SMEgg-PCX-]

@Window[The eggs of S. mansoni have lateral spine.]



@chapter[Diagnostics]
@Slide[Syringe-PCX-]

@Window[In this section, you will learn about various
diagnostic techniques in schistosomiasis control.
At the end of this chapter, you will understand
the strengths and weaknesses of each technique,
required resources for each technique and the
sources of supply.]

@Slide[Diag2-Text-Control programme-Sedimentation-Morbidity-Parasitology-Epidemiology-+-
Diagnosis/Faecal-Diagnosis/Parasitological-]
@Yellow[1.  Introduction]

A strategy of morbidity control for schistosomiasis control programme
requires appropriate parasitological and epidemiological criteria.
In the past the broad objective of schistosomiasis control has been to
stop transmission and qualitative parasitological techniques were generally
used for assessing results.

Qualitative parasitological techniques have generally been considered to be
simple, cheap and readily adapted to the needs of endemic countries. Simple
urine sedimentation requires only the container in which it is collected and
a pipette to remove the sediment. Sedimentation techniques for faecal
examination are more sophisticated. Some form of sieve to remove large
particles is necessary and sedimentation flasks and pipettes are essential.
The current costs of glass sedimentation flasks are surprisingly high.
0.5% Glycerine solution promotes effective sedimentation.

@Slide[Diag3-Text-Prevalence-Intensity of infection-Morbidity-]


While these sedimentation techniques may be sensitive, if a large unmeasured
volume is sedimented, lack of reproducibility, especially between different
examiners and lack of reliable estimation of the intensity of infection are
serious limitations for control programmes.  On the other hand, the presence
of gross haematuria, or microscopic haematuria can be recorded.  Thus data on
haematuria is a direct measure of morbidity and will strengthen data derived
from sedimentation technique.

The usefulness of quantitative techniques is now recognized by national
control programmes which have achieved significant reduction in prevalence
from double to single figures in large areas. As these programmes have
progressed, the prevalence became reduced to low levels and further
reductions from year to year were minimal. Prevalence data alone without the
support of data on the intensity of infection cannot be interpreted to mean
that control of morbidity is being achieved. Furthermore, data on the
intensity of infection are a useful indirect epidemiological indicator on
the level of transmission.

@SubSlide[Diag4-Text-Incidence-]

All parasitological diagnostic techniques are relatively insensitive in the
detection of low-level infections. This is an important consideration if
incidence data, the most precise indication of transmission, are to be
calculated. Quantitative parasitological diagnostic techniques provide
reproducible data which qualitative techniques cannot provide. Research on
immunodiagnostic techniques continues but none are currently recommended for
use in control programmes.

@Slide[Diag5-Text-Intensity of infection-Diagnosis/reagent-Filters-]
@Yellow[2.  Parasitological diagnostic techniques]

The diagnostic parasitological techniques have evolved in four stages. Since
the invention of the microscope, the results of microscopic examination of
urine or of faeces have been expressed as "positive" or "negative". The next
stage was an attempt to indicate the degree of intensity of infection by
using arbitrary plus signs: +, ++, +++. This classification has limitations.
The experts never agree and the beginners do not know how to select the
correct symbol.

In the third stage of development, a given volume of stool or urine was
examined by sedimentation or flotation techniques: the results were
expressed as the number of eggs per ml. These techniques are complex and
require special chemical reagents or sophisticated equipment.

Today we have entered a new area, which is not the final stage, for further
development will undoubtedly occur. WHO is now recommending urine filtration
techniques using filter supports with any of several types of filters
[including polycarbonate or NucleporeR nylon or NytrelR and filter paper]
and quantitative faecal thick smear techniques.

@Slide[Diag6-Text-Microscope-Quality control-Morbidity-]
@Yellow[2.1  Advantages]

           These quantitative techniques have numerous advantages:

     [1] they are rapid;
     [2] their cost is low;
     [3] they give reproducible results between technical personnel;
     [4] they provide an estimate of the intensity of infection;
     [5] they give quantitative results which can be submitted to
         statistical analysis;
     [6] they provide results which can be compared between different
         endemic areas and different observers;
     [7] some techniques allow samples obtained and prepared in the field
         may be examined microscopically later;
     [8] they facilitate quality control;
     [9] they are useful in the evaluation of morbidity related to
         Schistosoma infection;
    [10] they are important in the evaluation of schistosomiasis
         control activities devoted to reduction of morbidity.

@Slide[Diag7-Text-Urine-Stool-Cellophane-Excretion-Sensitivity-]
@Yellow[2.2  Limitations]

The major limitation of any diagnostic technique is the availability of
equipment and supplies. The small samples used in quantitative techniques
limit the sensitivity of the examinations. The recommended volume of urine
to be examined is 10 ml. The actual volume of faeces examined in the
cellophane faecal thick smear technique ranges from 10-125 mg. In public
health laboratories and hospitals sensitivity may be increased by examining
several thick smear slides prepared from the same specimen, or by examining
larger volumes of urine or stool.

In addition, there may be a day-to-day variability in egg excretion.

@Slide[Diag8-Text-]
@Yellow[2.3  The microscope]

The microscope is essential for all direct parasitological diagnostic
techniques. The microscopist should have specific training in the operation
and maintenance of the microscope. All microscopes should have reflecting
mirrors for use in daylight. If the microscope has only an electric light
source, there may be problems with the electricity supply or its stability
and with the replacement of light bulbs. Binocular microscopes may be
relatively inexpensive and are used more and more frequently. Regular
cleaning of the microscope lens and stage with a soft cloth is recommended.
Quantitative techniques require a fully operative mechanical stage to ensure
accurate scanning of the specimen. The stage should be regularly checked.

The microscope should have 10 x ocular (wide angle if possible) and a 10x
and a 40x objective.

@Slide[Diag9-Text-S. haematobium-S. japonicum-S. intercalatum-S. mansoni-]
@Yellow[2.4  Egg count categories]

Quantitative parasitological techniques permit the use of categories of egg
counts in the assessment of control programmes. A new dimension of
interpretation is added if such data are available. The units recommended
for reporting are:

 [1] the number of S. haematobium eggs per 10 ml of urine or;
 [2] the number of S. mansoni,  S. japonicum or S. intercalatum eggs per
     gram of faeces.

@Slide[Diag10-Text-]
@yellow[2.4.1  Urine examinations]

The quantitative data from urine examinations by the syringe filtration
technique for detection of S. haematobium infection may be reported
according to egg count categories. Population based epidemiological and
clinical studies have assessed the relationship between proteinuria or
haematuria and S. haematobium infection. In most of these studies a high
proportion of children excreting more than 50 eggs per 10 ml of urine have
haematuria and/or proteinuria as detected by chemical reagent strips.
Limited experience is available on the use of the following categories and
modification may be required to include a third higher egg count category.
All categories must be adapted to different endemic countries.

           ╔══════════════════════╤════════════════════════╗
           ║ Level of infection   │       No. of eggs per  ║
           ║                      │       10 ml of urine   ║
           ╟──────────────────────┼────────────────────────╢
           ║     Light            │            1-49        ║
           ║                      │                        ║
           ║     Heavy            │            50 +        ║
           ╚══════════════════════╧════════════════════════╝

@Slide[Diag11-Text-]



Two additional reasons for selecting 50 eggs per 10 ml of urine as an upper
limit for urinary egg counts are: (1) the lack of reproducibility of higher
counts between microscopists or by the same microscopist, and (2) the length
of time required to count more than 50 eggs. In training courses on
quantitative parasitological techniques, it has been our experience that the
accuracy of higher egg counts is low. Nytrel and Nuclepore filters (or even
paper filters if staining is done quickly) may be examined immediately to
identify a person for treatment.

@SubSlide[Diag12-Text-]

A third category such as 500+ or 1000+ S. haematobium eggs per 10 ml of
urine, may be appropriate in areas where the intensity of infection
frequently (> 10%) reaches this level. This decision should be based on a
trial in which microscopists are trained to estimate accurately high egg
counts by different methods. If the microscopist recognizes that the filter
has more than 50 eggs, then he may (1) scan the entire filter or (2) scan
only one quadrant of the filter to determine if more than 125 or 250 eggs
are present in the quadrant and multiply his estimate in the quadrant by 4
to obtain the total number of estimated eggs on the filter. Other methods of
estimating high egg counts may also be evaluated.

Most control programmes using large-scale chemotherapy did not foresee that
prevalence and intensity of infection could be reduced so rapidly. For this
reason, the use of quantitative parasitological techniques from the outset
is desirable in order to avoid the administrative difficulties of
introducing a new parasitological technique and reporting methodology after
the programme has expanded.

@Slide[Diag13-Text-]
@Yellow[2.4.2  Stool examinations]

The quantitative data from stool examinations for detection of S. mansoni,
S. japonicum or S. intercalatum eggs may be reported according to egg count
categories. These categories are derived from population based
epidemiological studies which assessed the relationship between intensity of
infection and morbidity, i.e. liver and spleen size. In children liver and
spleen enlargement correlate with the intensity of infection. Most
epidemiological studies agree that the correlation becomes statistically
significant at 100 S. mansoni or S. japonicum eggs per gram of faeces or
greater.

@Slide[Diag14-Text-]

As an example the egg counts obtained by the cellophane faecal thick
smear technique (Kato-Katz) may be reported in the following categories:

    ╔═════════════════════╤════════════════════╤══════════════════════╗
    ║ Level of infection  │  No. of eggs per   │   Range of eggs per  ║
    ║                     │  Kato-Katz slide   │   gram of faeces     ║
    ╟─────────────────────┼────────────────────┼──────────────────────╢
    ║   Light             │       1-4          │       24 - 96        ║
    ║                     │                    │                      ║
    ║   Moderate          │       5-33         │      120 - 792       ║
    ║                     │                    │                      ║
    ║   Heavy             │       34+          │         816+         ║
    ╚═════════════════════╧════════════════════╧══════════════════════╝

In some endemic areas intermediate categories may be useful such as:
5-16 eggs per slide or 120-384 eggs per gram of faeces; 17-33 eggs per slide
or 408-792 eggs per gram of faeces. These categories may have to be adapted
according to the general intensity of infection in a given area. If few
infections over 800 eggs per gram of faeces are present, the use of
intermediate categories may be appropriate.

@SubSlide[Diag15-Text-]

In some endemic areas the intensity of infection may be rarely over 100 eggs
per gram of faeces either naturally or due to an advanced stage of control.
In such areas the sensitivity of a single Kato slide is insufficient to
detect all infected persons. In these areas multiple Kato slides may be
prepared to increase the sensitivity or a more elaborate technique such as
the quantitative modified formol-ether concentration technique may be used.
The rates of morbidity due to schistosomiasis are low in these areas. Public
health and hospital laboratories could maintain adequate monitoring and
surveillance by using more sensitive techniques. Specialized schistosomiasis
control activities in areas of low intensity of infection are probably not
necessary unless there is a risk of spread of schistosomiasis due to
migration or man made water resource projects or the control of transmission
is desired.

@Slide[Diag16-Text-]
@Yellow[3.  Indirect diagnostic techniques]

Simple indirect diagnostic techniques to identify heavily infected persons
particularly children, will aid the implementation of schistosomiasis
control programmes. Such techniques may be used by minimally trained
personnel. Rapid low cost diagnosis of heavily infected persons followed by
treatment with new safe and highly effective antischistosomal drugs will
reduce morbidity related to schistosomiasis at costs within the financial
constraints of most endemic countries. The cost effectiveness of indirect
techniques has not yet been evaluated in large-scale programmes.

@Slide[Diag17-Text-]
@Yellow[3.1  Urinary blood]

Diagnostic reagent strips which indicate semi-quantitative levels of blood
and protein ix the urine became commercially available about 25 years ago.
The current range of sensitivity of the available strips is 5-15 intact red
blood cells per microliter and 0.015-0.03 mg of haemoglobin per 100 ml of
urine. All strips measuring blood in the urine utilize similar chemical
reagents: a peroxide compound and 0-toluidine as the chromogen.

The colour distinction between negative and the first level of reactivity is
well defined. The colour indicators for the presence of blood are usually
distinct changes from yellow or pale orange to green or blue.

False positive reactions have been observed due to myoglobinuria or to
bacterial peroxidases due to heavy bacteriuria. If the urinary ascorbic acid
levels are above 10 mg/100 ml of urine, inhibition of the reaction may be
observed.

@SubSlide[Diag18-Text-]
@Yellow[3.2  Urinary protein]

Reagent strips which measure semi-quantitative levels of protein,
principally albumin, in the urine utilize tetrabromophthalein ethyl ester
with a buffer. The colour discrimination between negative and the first
level of proteinuria, usually 10-25 mg of protein/100 ml of urine, is not
clearly defined. The usual colour change from yellow/green to green or blue
may be subtle and difficult to assess precisely at the intermediate ranges
of proteinuria.

False positive reactions may occur in urines containing an alkaline, quinine
or a quinine derivative. False negative reactions have been observed in
strongly acid urines and urines with Bence-Jones proteins or predominant
gamma globulin excretion.

@Slide[Diag19-Text-]
@Yellow[3.3  Sensitivity and specificity]

The reagent strips have been evaluated according to sensitivity and
specificity compared with quantitative parasitological techniques in
different age groups. In several studies, 80% of infected children had
haematuria and of those with more than 50 eggs per 10 ml of urine, about
98-100% had haematuria. In adults the proportion of infected persons with
haematuria was lower.

@Slide[Diag20-Text-]

    ╔═══════════════════════════════════════════════════════════════╗
    ║     Sensitivity and specificity of chemical reagent strips    ║
    ║                in children 14 years or younger                ║
    ╟───────────────────────────────────────────────────────────────╢
    ║                 Sensitivity                Specificity        ║
    ║                                                               ║
    ║   Haematuria        80%                        85%            ║
    ║                                                               ║
    ║   Proteinuria        7%                        37%            ║
    ╚═══════════════════════════════════════════════════════════════╝
    ╔═══════════════════════════════════════════════════════════════╗
    ║     Sensitivity and specificity of chemical reagent strips    ║
    ║              in adults 15 years of age and older              ║
    ╟───────────────────────────────────────────────────────────────╢
    ║                 Sensitivity                Specificity        ║
    ║                                                               ║
    ║   Haematuria        57%                        89%            ║
    ║                                                               ║
    ║   Proteinuria       32%                        59%            ║
    ╚═══════════════════════════════════════════════════════════════╝

@SubSlide[Diag21-Text-]

These results are similar to published findings which indicated that the
measurement of haematuria alone is sufficient to identify infected persons,
particularly children, during large-scale surveys. The low specificity of
the protein reading may not be so in all endemic areas. In each endemic
area, the reagent strips available should be evaluated under local
conditions and the data analyzed according to quantitative urinary egg
counts by age and sex. It is not sufficient to accept data from other
endemic areas.

The reasons for deciding whether or not to include urinary protein
measurements should also be evaluated locally. Combined reading of
haematuria and proteinuria has been recommended. The following should be
considered:

     (1)     it is difficult to train field personnel to read
             correctly the protein portion of the reagent strip
     (2)     the increased specificity of the combined reading is
             associated with a reduced sensitivity.

@SubSlide[Diag22-Text-]
@Yellow[3.4  Blood in faeces]

A number of reagents are available. None of them have been evaluated on a
large scale to identify persons infected with S. mansoni, S. intercalatum,
S. japonicum or S. mekongi.

@slide[Diag23-Text-]
@Yellow[4.  Indirect screening procedures]

The combination of:

     (1)     previous history of haematuria

     (2)     observation of the urine specimen for gross haematuria,
             i.e. bloody red or cloudy brown urine

     (3)     presence of haematuria as detected by the reagent
             strip.

has been suggested for use under field conditions to identify rapidly
heavily infected persons, particularly children.

@Slide[Diag24-Text-]

If a question on the history of haematuria is to be used, the formulation of
the question and the replies to it must be carefully evaluated. It is
necessary to have a good understanding of local customs and their effects on
verbal replies to questions. The age at which reliable answers can be
expected should be determined. The question should be phrased: "Have you
ever had blood in your urine" or something similar. It may be necessary to
define if the haematuria is of recent onset or occurred many years in the
past. In areas where chemotherapy has not been previously available, this
question has proved an extremely sensitive indicator of actual infection in
children.

Observation of the urine specimen so as to detect a bloody or a cloudy brown
appearance can be expected to identify up to 15% of infected children in
schools of some endemic areas. This simple observation may reduce the use of
chemical reagent strips and accelerate the rate of identification of infected
children. in every endemic area this variable should be evaluated in adults
as well. Chronic bladder lesions due to S. haematobium or other diseases of
the genitourinary tract may cause gross haematuria; the frequency of these
lesions should be determined before this approach is applied in the field.

@Slide[Diag25-Text-]

The appropriate sequence of screening procedures and hence the quantity of
reagent strips required will vary according to the epidemiological
characteristics of each population surveyed. The following possible screens
may be considered.

Screen I
     1.      History of haematuria
     2.      Observation of the urine for blood
     3.      Presence of blood by reagent strips

Screen II
     1.      Presence of blood by reagent strips
     2.      Observation of the urine for blood
     3.      History of haematuria

Screen III
     1.      Observation of the urine for blood
     2.      Presence of blood by reagent strips

@Slide[Diag26-Text-]

It should be noted that in areas of low prevalence, many reagent strips would
be used to detect one case of urinary schistosomiasis. Thus the use of
reagent strips to identify persons with S. haematobium infection should be
carefully evaluated in each endemic country before large-scale use is
recommended.

In some endemic areas, a history of dysuria (painful micturition) has been
associated with S. haematobium infection. inclusion of this question has not
been fully evaluated under field conditions.

@SubSlide[Diag27-Text-]
@Yellow[5.  Miracidial hatching techniques]

These are sensitive techniques for the detection of schistosomal infection.
In clinical trials of antischistosomal drugs, hatching techniques are useful
to determine viability of Schistosoma eggs. These techniques have not been
well standardized and further improvements are needed.

@Slide[Diag28-Text-]
@Yellow[6.  Survey procedures]

The diagnostic parasitological techniques will be used in several different
contexts. Trained laboratory technicians in public health or hospital
laboratories will be responsible for the routine examinations as well as
surveys done in proximity to the laboratory. High standards of reporting and
supervision are essential in these facilities. Within schistosomiasis control
programmes specialized teams may undertake periodic systematic population or
school surveys. The composition of these teams will vary according to the
needs of each endemic country.

      Country X                                         Country Y

        1   (doctor of medicine) Supervisor                 1
        2                        Microscopist               2
        2                        Laboratory aid             2
        2                        Record clerk               1
        1                        Motivator/nurse
                                 Community worker           1

@Slide[Diag29-TEXT-]

If the team is mobile, the drivers should be trained in laboratory and
survey tasks. Some of the best microscopists started their public health
careers as drivers.

The tasks of each member of the team should be defined and specific
training given (see section 6.5).

Community workers, i.e. local residents appointed by the community to serve
as their liaison with the team, should be trained to work with a team, to
define the epidemiologically important transmission sites and to promote the
health education programme. This type of person has been designated the
"Schistosomiasis agent" in one country.

@Slide[Diag30-Text-]
@Yellow[6.1  Data recording]

The first step in proper data recording is to write the number clearly. All
field personnel should have a brief training in completing record forms
clearly and neatly. This is a simple exercise which is often ignored.
Statistical methods applicable to schistosomiasis control programmes are
discussed in a separate document (i.e. "Statistic al methods applicable to
schistosomiasis control programmes" by H. Dixon. WHO/SCHISTO/85.81 -
WHO/ESM/85.1).

Recording forms are completed at the time a specimen is submitted or an
examination is performed. A summary report form should be completed for
reporting the results of a survey.

This form was designed to facilitate reporting both prevalence and intensity
of infection, as it is the actual number of eggs counted which is reported.
At the higher supervisory levels the actual faecal egg counts can be
transformed to eggs per gram of faeces if required.

@Slide[Diag31-Text-]
@Yellow[6.2  Operational efficiency]

@Yellow[6.2.1  Work bench]

Proper organization of the supplies and equipment on the work bench or table
to undertake parasitological examinations will greatly increase operational
efficiency. All training programmes should include simple exercises in
organizing the work bench. If the same person is responsible for preparing
the specimen as well as performing the microscopic examination he/she must
be well organized and efficient. The community is very observant about the
efficiency of field operations. In rural communities time is valuable, and
agricultural workers do not like to wait in long inefficient lines. An
efficient field operation will promote cooperation by the community.

Sturdy durable tables and chairs are needed. Sometimes these can be obtained
ix the community. If this equipment is to be provided by the community, a
previous visit by the operations' supervisor should ascertain if the
equipment is available and if it is adequate. The height of the table and
chairs should be checked, etc.

Several diagrams are presented in Annex 7 as suggested organization work
bench plans. Checklists of equipment are useful so as to ensure that no
equipment or supplies are missing when the team arrives in the field.

@Slide[Diag32-Text-]
@Yellow[6.2.2  Surveys]

Diagnosis and treatment surveys in schistosomiasis programmes will be
undertaken most efficiently in the community. by doing the survey in the
community itself the cost of transporting specimens to a central laboratory
and of returning the results as well as the diminished rate of follow-up for
treatment are important considerations in favour of community or school
based operations. School age children are a priority group for diagnosis and
treatment surveys. School surveys may be done rapidly if they are carefully
planned and well organized.

Prior to any field survey, days or weeks in advance if necessary, the
community or school should be visited and the purpose of the survey
explained accompanied by a health education presentation and discussion.
During the preliminary visit, the actual survey should be diagrammed.

Many options exist for the collection of stool specimens for microscopic
examination. Containers may be delivered to the house and picked up at a
later time or at a central collecting point.

@Slide[Diag33-TEXT-]

The containers may be kept at a central point where the population may
provide these specimens immediately. The community may be advised of the
availability of diagnosis and treatment and may bring these specimens in
home made or casual containers.

The selection of the proper type of collection container xs an important
administrative decision in a control programme. An ideal container has a
wide mouth, is easily marked with marking pens and labels stick easily to
its surface. A reusable container may be a good long term investment. If
disposable containers are selected they should be degradable. In general a
standardized container is more desirable than casual home containers.

Simple operational flow diagrams may be made for each site where surveys
are to be done. Forward planning will save the time of the field team and
that of the persons participating in the survey.

@Slide[Diag34-Text-]
@Yellow[6.3  Supervision]

Supervision of field teams is an important component of a schistosomiasis
control programme. The tasks of supervisors must be specified so that they
can effectively carry out their responsibilities.

Quality control of the work of the microscopists requires patience and tact.
In S. haematobium surveys, the urine specimen containers are usually kept at
the treatment table. A satisfactory procedure for quality control is for
every 10th urine specimen to be given to someone who has completed treatment
and request him to go back in line for examination.  The microscopist will
record the result usually without realizing that the specimen has been
examined before. The supervisor can then verify if the two results of the
specimen are the same.

Other procedures for quality control max be used such as systematic
reexamination of every 10th - 30th slide by an independent microscopist. It
is important to maintain the "esprit de corps" of the microscopists by
having positive slides available to check the accuracy of the egg counts.

@Slide[Diag35-TEXT-]
@Yellow[6.4  Training]

Most quantitative parasitological techniques can be learned after a few
hours of intensive training. Following one or two demonstrations trainees
should be observed closely as they repeat the procedure until they are
able to manipulate the equipment and obtain adequate preparations.

Periodic retraining of field personnel by supervisors is necessary. Bad
habits tend to creep into the routine work if supervisors do not spend
time to correct small details of performance.

@SubSlide[UrineFilt1-TEXT-]
@Yellow[7. Urine filtration technique for quantitative or qualitative diagnosis of]
@Yellow[   Schistosoma haematobium infection]

Urine should be collected between 11 a.m. and 2 p.m. to coincide with the
peak urinary excretion of Schistosoma haematobium eggs.  The urine may be
collected in any type of wide mouthed container.

Each sample is mixed by drawing urine in and out of a disposable plastic
syringe with a 5 cm extension of straight plastic tubing of the same diameter
as the needle adaptor. 10 ml of urine is withdrawn in the syringe.  The
extension tube is removed and the urine is injected through a 13 mm (or 25 mm)
diameter Swinnex filter support containing a 13 mm (or 25 mm) diameter Nytrel
TI 20 HD filter (20 micron mesh size). Once the urine has been completely
expressed from the syringe, the syringe is removed, filled with air and
reinjected into the filter holder. This procedure is repeated twice to remove
excess urine and to force the eggs to adhere to the surface of the filter.

@SubSlide[UrineFilt2-TEXT-]

The filter support is then opened and the filter removed with forceps and
placed face upwards on a glass slide. In order to observe the eggs on the
filter without stain, one drop of saline is pipetted onto the filter to
prevent drying. A drop of Lugol's iodine solution (i.e. iodine, 1 gram;
potassium iodide, 2 grams; distilled water, q.s 100 ml) effectively strains
the eggs and is the best method for visualization of the eggs. In the
El-Zogabie modification, the filters are covered with cellophane soaked in
glycerine/malachite green solution (see Annex 2) and preserved for reading
several days afterwards.

Microscopic examination is performed under 10x magnification and the number of
eggs on the entire filter may be counted and recorded. For semi-quantitative
examinations, up to 50 eggs may be counted; over 50 eggs per 10 ml urine may
be considered as heavy infection.

The same procedure may be followed with the Nuclepore filters except that the
filter is placed face downwards on the glass slide and is not re-used. After
addition of one drop of glycerine or mounting media, the Nuclepore filter may
be kept in microscope boxes for later evaluation.

@SubSlide[UrineFilt3-Text-]
@Yellow[7.1  Urine specimen containers]

Any type of plastic snap-top or easily sealed container is acceptable. It is
most appropriate to obtain suitable containers from local suppliers.

@Yellow[7.2  Transport boxes]

If the urine specimens are to be transported, small, shallow, wooden boxes
which can be stacked are appropriate. These can be constructed locally after
the size of the containers has been determined.

@Yellow[7.3  Urine examination]

@Yellow[7.3.1  Plastic disposable syringes, 10 ml]

For purposes of urine filtration, 10 ml re-usable plastic syringes are
adequate. A Luer-slip tip, centrally located (not eccentric) is recommended.
These are available from:

      Becton Dickinson, Division of Becton, Dickinson and Company,
      Rutherford, New Jersey 07070, USA.

@SubSlide[UrineFilt4-Text-]
@Yellow[7.3.2  Plastic tube extension]

To avoid immersing the syringe in the urine specimen, the use of a 5 cm
plastic tube extension fitted to the Luer-slip tip is suggested. The internal
diameter of the tube should be 1/8 inch (0.3 cm). Intravenous tubing may also
be used. To form a permanent fit, the end of the tube extension should be
heated slightly in an alcohol burner, then fitted onto the tip of the syringe.
Tubing is available from:

      Arthur H. Thomas Co, P.0. Box 779, Philadelphia, PA 19105, USA.
      Item: No. 9565-L42 Tubing, low density polyethylene tubing 1/8" x 1/16",
      100 ft roll

@SubSlide[UrineFilt5-TEXT-]
@Yellow[7.3.3  Swinnex filter supports]

These are available in 13 or 25 mm diameters. The larger diameter holder is
recommended only for examination of urine with excessive sediment by Nuclepore
filtration. If Nytrel filters are used, the 13 mm filter support is adequate
for all examinations. These filter holders are available from:

     Millipore Corporation, Bedford, MA 01730, USA
     or
     Millipore SA, Zone Industrielle, 67020 Molsheim, France

     Items:  SX 00 01300 - Swinnex 13 mm
             SX 00 02500 - Swinnex 25 mm

     Item:   Large volume purchases of packages of 500 Swinnex
             13 mm filter supports are available at a special
             price by ordering directly from Specials Coordinator
             Millipore Corporation, under order number SE1M 276 A4

@SubSlide[UrineFilt6-TExt-]
@Yellow[7.3.4  Filters]
@Yellow[7.3.4.1  Nytrel]

This is a woven, polyamide, monofilament material which is available in
various mesh sizes. The 20 micron pore size has been used successfully for
filtration of S. haematobium eggs. The appropriate filter size may be cut by
hand or punched from material purchased by the square metre. Available from:

     L'Union Gazes x Bluter, B. P. 2, 42360 Panissixres, France

     Item: Nytrel TI HD 20 in rolls per m2 or precut 12 mm diameter in
           packages of 500 filters.

Comment.  This filter is low-cost, re-usable after washing with common
detergents or plain running water over 5,000 times in field conditions.
Examination must be performed shortly after preparation. The sample cannot be
preserved. Best for rapid field surveys in which high sensitivity and
quantitation are required. no staining is necessary. A light microscope with
mirror/sunlight source is optimal. The Nytrel filters tend to dry rapidly and
require moistening with a drop of saline or Lugol's solution to permit
adequate visualization of the eggs.

@SubSlide[UrineFilt7-Text-]
@Yellow[7.3.4.2  Nuclepore]

A polycarbonate membrane filter which comes in various pore sizes ranging from
8 to 14 microns and in pre-cut 13 or 25 mm diameter filters or in 8 x 10 inch
sheets from which filters may be punched. Available from:

      Nuclepore Corporation, 7035 Commerce Circle, Pleasanton, CA 94566, USA

Public sector or large volume purchases of Nuclepore filters should be
directed to:

      PATH, Program for Appropriate Technology in Health, Canal Place,
      130 Nickerson Street, Seattle, WA 98109, USA

@SubSlide[UrineFilt8-Text-]

Comment. This filter is relatively expensive if purchased already pre-cut.
Cost may be reduced by punching filters from 8 x 10 inch sheets. Cost is the
only drawback for use in large-scale surveys. Only the 12 or 14 micron pore
size are recommended for field work. The smaller pore sizes may clog with
blood or other sediment. Under dry conditions, it may be necessary to place a
drop of saline or glycerine on the filter to visualize the eggs adequately.
The filter may be preserved by adding one drop of glycerine to the slide at
the time of preparation; fixation of the filter to the slide with tissue
mounting media (Permount) or covering the filter with cellophane from the
Kato-Katz technique is ideal for accurate quantitative examination in
research. The membrane is delicate and may be re-used several times if care is
taken in washing with detergent.

Items:   12 micron pore size - No. 110416, 13 mm filter
                               No. 110616, 25 mm filter
                               No. 113616,  8 x 10 sheets (100)
         14 micron pore size - No. 110417, 13 mm filter
                               No. 110617, 25 mm Filter
                               No. 113616, 8 x 10 sheets (100)

@SubSlide[UrineFilt9-Text-]
@Yellow[7.3.4.3  Paper filters]

Whatman No. 541 or No. 1 paper filters of 1x or 25 mm diameter have also been
used with iodine (Plouvier et al., 1975; see section 4) or ninhydrin (Bradley,
1968; see section 4) staining in syringe urine filtration techniques.

Suppliers. This type of filter paper can be ordered from any laboratory supply
company. Further information can be obtained from the Centre de Recherches sur
les Méningites et les Schistosomiases (CERMES), B.P. 10887, Niamey, Republic
of Niger.

Comment. The paper filters are inexpensive and may be stored for later
examination. This aspect may be important for quality control of the
quantitative microscopic urine examinations. Under some conditions ninhydrin
may not stain the eggs properly. Bell (personal communication, 1983) has
suggested pre-staining with saturated potassium iodide (2 ml in 250-500 ml of
urine) before filtration followed by staining the filter paper with ninhydrin.

The cost of the paper filter technique is mainly the cost of the stain. Urines
with heavy sediment or haematuria may not pass through the paper filter and
the sediment may obscure visualization of the S. haematobium eggs.

@SubSlide[UrineFilt10-Text-]
@Yellow[7.3.5  Filter punch]

Either 13 or 25 mm filter punches are available to punch either Nytrel,
Nuclepore or paper filters from:

     Bugnard Cie, Chemin de Montely 46, CH-1000 Lausanne 20, Switzerland
     Item: No. 24.620 (specify size of punch needed)

     or

     C. S. Osborne & Co, Harrison, NJ 0729, USA
     Article No. 149 Arch Punch

@SubSlide[UrineFilt11-Text-]
@Yellow[7.3.6  Forceps]

Flat forceps are recommended to handle the filters. Available from:
     Arthur H.,Thomas Co, P. 0. Box 779, Philadelphia, PA 19105, USA
     Items: No. 5-17-G15, forceps membrane (1980 catalogue)
            No. 5117-F20, forceps

@Yellow[7.3.7  Microscope slides]

Though standard laboratory items, these must be available. microscope slides
sized 2 x 3 inches (5 x 8 cm) may be used to examine six to eight 13 mm
filters at a time.

@Yellow[7.3.8   marking pencils]

These are useful for identifying slides and for marking containers. Wax
pencils are the cheapest.

@SubSlide[UrineFilt12-Text-]
@Yellow[7.3.9  Hand tally counters]

Accurate egg counts are facilitated by using hand tally counters which can be
obtained from all equipment supply agents, for example:

     Arthur H. Thomas Co, P. 0. Box 779, Philadelphia, PA 19105, USA
     Items: No. 3297-H50, counter
            No. 3297-H60, counter, hand tally
     and

     Fisher Scientific Company, 711 Forbes Avenue, Pittsburgh, PA 15219, USA
     Item:  No. 7-905, counter

@Yellow[7.3.10  Accessories]

Pasteur pipettes, rubber bulbs and small beakers may be needed to keep water
for moistening the filters at the time of microscopy.

@SubSlide[CellFaec1-Text-]
@Yellow[8. Cellophane faecal thick smear examination technique for diagnosis of]
@Yellow[   intestinal schistosomiasis]

The cellophane faecal thick smear examination technique was introduced by Kato
and Miura in 1954 (see section 7). Subsequent to the first English publication
of this technique by Komiya and Kobayashi in 1966 (see section 7), many
modifications of the original technique have appeared. This technique has
proved to be a useful and efficient means of diagnosis of intestinal
helminthic infections, as well as of Schistosoma mansoni and S. japonicum.

@SubSlide[CellFaec2-Text-]
@Yellow[8.1  Materials]

(a)   Glass microscope slides.  The ordinary slides 25 x 75 mm are
      appropriate.
(b)   Flat-sided wooden applicator sticks or similar devices made of plastic
      or other material.
(c)   Cellophane, wettable, 40 to 50 microns in thickness in 22 (or 25) mm x
      30 to 35 mm strips
(d)   Glycerine-malachite green solution (50% solution)
      - 100 ml water
      - 100 ml glycerine
      - 1 ml 3% aqueous malachite green or 3% aqueous methylene blue
(e)   Screen. Made of either wire steel cloth (105 mesh, stainless steel,
      bolting cloth) or plastic (60 mesh per square inch or 250 x mesh size).
      A stainless steel screen welded onto an oval steel ring with a handle is
      re-usable.
(f)   Template. Made of stainless steel (Peters et al., 1980, see section 7),
      plastic (Kato-Katz) or cardboard (Japanese Association of Parasite
      Control) templates of varying diameters have been used. The size (20 mg
      to 50 mg) may depend on local requirements; in any event, the template
      permits accurate delivery of a standard stool specimen and determination
      of quantitative egg counts.

@SubSlide[CellFaec3-Text-]
@Yellow[8.2  Procedure]

(a)   Soak the cellophane strips in the 50% glycerine-malachite green
      (methylene blue) solution for at least 24 hours before use.
(b)   Transfer a small amount of faeces onto a piece of scrap paper (newspaper
      is ideal).
(c)   Press the screen on top of the faecal sample.
(d)   Using the flat-sided wooden (or plastic) applicator, scrape across the
      upper surface of the screen to sieve the faecal sample.
(e)   Place a template on a clean microscope slide.
(f)   Transfer a small amount of sieved faecal material into the hole of the
      template and carefully fill the hole. Level flat with the applicator
      stick.
(g)   Remove the template carefully so that all the faecal material is left on
      the slide and none is left sticking to the template.
(h)   Cover the faecal sample on the slide with a glycerine soaked cellophane
      strip.
(i)   If an excess of glycerine is present on the upper surface of the
      cellophane, wipe off the excess with a small piece of toilet paper or
      absorbent tissue.

@SubSlide[CellFaec4-Text-]

(j)   Invert the microscope slide and press the faecal sample against the
      cellophane on a smooth surface (a piece of tile or flat polished stone
      is ideal) to spread the sample evenly.
(k)   Do not lift the slide straight up. The cellophane may separate. Gently
      slide the microscope slide sideways holding the cellophane.

Preparation of the slide is now complete. It may be necessary to wipe off
excess glycerine with a piece of toilet paper to assure that the cellophane
stays fixed. After practice you can obtain perfect preparations.

Several modifications have been developed in control programmes. In Malawi,
metal sieves with 100 mesh screen are used and the specimen is forced through
the screen. The sieve is rotated so that 20 specimens can be sieved
consecutively. (Details may be obtained from: National Bilharzia Control
Programme, P.0. Box 377, Lilongwe, Malawi.) In Burundi, small individual
sieves have been manufactured and the specimen, on a small piece of plastic,
is forced through the screen. (Details may be obtained from: Projet
Bilharzioses, B.P. 337, Bujumbura, Burundi.)

@SubSlide[CellFaec5-Text-]
@Yellow[8.3  Proper reading of slides]

The slide should be kept at ambient temperature for at least 24 hours before
microscopic examination (see below regarding hookworm eggs). By placing the
slide in an incubator (400c) or under an intense fluorescent, incandescent
light in the laboratory or in sunlight in the field, the slide may be read
within minutes.

To facilitate the microscopic reading, one or two drops of eosin in saline
(1:100) may be placed on the upper surface of the cellophane, left for 3 to 5
minutes, then wiped off with a piece of toilet paper or absorbent paper. This
method permits improved visualization of Schistosoma eggs.

Microscopic reading of the cellophane thick smear slides should be easily
accomplished with 1OX wide field ocular and 1OX objectives. Confirmation of
identification of S. mansoni and S. japonicum eggs may be required by the 40X
objective. Eggs of ascaris lumbricoides, Trichuris trichuris and Fasiolopsis
buski are easily visualized by this technique. This technique has also been
used to identify Clonorchis sinensis, Metagonimus yokogawai, opisthorchis
viverrini, Fasciola hepatica, Hymenolepis nana and Taenia spp. Hookworm eggs
may be detected only immediately after preparation of the slide.

@SubSlide[CellFaec6-Text-]

Many different recommendations have been made regarding reading of the slides.
Ideally, each laboratory would review the reading procedure carefully to
determine the optimal time for microscopic examination of the slides.

All results should be recorded as number of S. mansoni or S. japonicum eggs
per gram of faeces. According to the size of the template, the number of eggs
counted on the slide will be multiplied by a correction factor to obtain the
number of eggs per gram of faeces. The Kato-Katz template delivers 41.7 mg of
faeces; the correction factor is 24.

@SubSlide[CellFaec7-Text-]
@Yellow[8.4  Shipment and storage of the slides]

Cellophane thick smear slides can be prepared in the field, stored in
microscopic slide boxes and shipped great distances, which permits examination
at a central laboratory if required.

Under most conditions, if the proper grade of cellophane and adequate
concentration of glycerine are used, slides can be kept up to six months
without deteriorating. If the cellophane curls or dries, it can be remoistened
with a drop of water, glycerine or eosin in saline. Reconstitution is not
perfect but at least practical. Again, each laboratory can adjust these
recommendations for storage according to individual requirements.

@SubSlide[CellFaec8-Text-]
@Yellow[8.5  Thick or hard stool specimens]

The major complaint about the thick smear technique from most microscopists
has been that it is impossible to visualize the helminth eggs in some hard
(constipated) stool specimens. In such cases:

(a)   after preparation by the standard method, be sure to wait 24 or 48 hours
      before counting eggs on these slides. The slide may clear slowly;

(b)   remake another pair of samples on a large (2 x 3 inches - 5 x 7.6 cm)
      microscope slide and use a slightly larger piece of cellophane (35 x 35
      mm), then press very hard to flatten the specimen as much as possible.

(c)   when the large slide is used, the stool may be softened with saline or
      glycerine before sieving.

@SubSlide[CellFaec9-Text-]
@Yellow[8.6  Suppliers]

@Yellow[8.6.1  Wettable cellophane]

     (a) Description: No. 124PD, thickness 33 u, weighs approximately 50 g/m2
         Bulk supplier: E. I. Dupont Nemours Plastic Products and Resins Dept
                        Wilmington, Delaware 19898, USA

     (b) Description: Rhone Poulenc 500 P 601
         Bulk supplier: Rhone Poulenc S.A., France

     Product supplier (i. rolls of 50 meters x 22 mm):

     Societé Normande de Coupage (in lots of 1000 only)
     72 rue des Chênaux, Ymare, 76520 Boos, France

@SubSlide[CellFaec10-Text-]
@Yellow[8.6.2.  Screen]

     (a) Stainless steel
     Item characteristics: 105 mesh, stainless steel, bolting cloth
     Supplier: W. S. Tyler Inc., 8200 Tyler Boulevard, Mentor, OH  44040, USA

     (b) Nylon screen
     Item characteristics: TI250, HD 16243 A
     Supplier: L'Union Gazes à Bluter, B.P. 2, 42360 Panissixres, France

     (c) Plastic screen
     Item characteristics:  60 mesh/sq. inch (CS-5)
     Supplier: Japanese Association of Parasite Control Co.
               Hokenkaikan, 1-I Ichigaya-Sadohara Shinjuku-ku, Tokyo, Japan

@SubSlide[CellFaec11-Text-]
@Yellow[8.6.3  Complete kit including all necessary material]

     (a) Japanese Association of Parasite Control c/o Hokenkaikan
         1-I Ichigaya-Sadohara
         Shinjuku-ku, Tokyo, Japan

     (b) Helm-Text kits (Kato-Katz) for 100 or 500 examinations
         A.K. Indústria e Comércio Ltda
         rua Goitacazes 43-8 andar
         CEP 30000 Belo Horizonte, M.G.
         Brazil
         Telephone [phone]

(Note: the glycerine/malachite green solutions of the kits may be defective
and should be discarded and replaced by fresh solution.)

@SubSlide[GlassFaec1-Text-]
@Yellow[The glass sandwich faecal thick smear technique for diagnosis of intestinal]
@Yellow[schistosomiasis]

The glass sandwich technique is a further modification of the glass coverslip
thick smear technique first described by Teesdale and Amix in 1976 (see
section 5). This technique and the cellophane thick smear technique may be
compared under field conditions prior to selecting the most suitable
technique.

The essence of the glass sandwich method is that, after sieving of the stool
sample to remove large particles, the glass cover slide enables the
investigator to press the stool sample into an even layer, in which the eggs
can be seen clearly against a background of the rest of the stool matrix. No
clearing is therefore required and the stool can be examined immediately.
however, preservation of the slide for later reading is not possible.

@SubSlide[GlassFaec2-Text-]

There are three drawbacks to this rapid low cost technique:

     (1) if the stool specimen contains small hard particles such
     as sand which are not removed by sieving, the slides will
     not stick together;

     (2) the large slide may be difficult to manipulate on a
     mechanical stage.

     (3) the performance of the microscopists requires intensive
     training and supervision. An experienced microscopist with a
     broad training in parasitology usually has no difficulty in
     identifying the eggs.

@SubSlide[GlassFaec3-Text-]
@Yellow[1.  Materials]

  (a) Glass microscope slides 2 x 3 inches (5 x 7.6 cm) are most appropriate

  (b) Squares of paper 5 x 5 cm.

  (c) Flat sided applicator sticks (wood or plastic).

  (d) Metal frame sieves, 100 mesh (150 microns). Eight inch (20.3 cm)
  diameter sieves (obtainable from Endecotts Ltd, Lombard Road,
  London SWl9 3VP, England) are very satisfactory, but any netting of 150
  microns on a frame will suffice.

  (e) Templates of stainless steel (Peters et al., 1980) or plastic
  (Kato-Katz) can be used. The size of the hole will depend on local
  requirements. Templates enable an accurate amount of stool to be delivered
  so that quantitative egg counts can be made.

  (f) Counting grids (optional). These can be made of either transparent
  plastic or glass. Lines should be spaced 0.125 inches (0.357 cm) apart so
  that one complete square fills the microscopic field of view at 40x
  magnification. Grids enable accurate counting.

@SubSlide[GlassFaec4-Text-]
@Yellow[2.  Procedure]

     (a) Using an applicator stick, transfer a small sample of
     the stool to be examined (about the size of a maize kernel
     or large pea) onto a piece of paper 5 x 5 cm. A cut-off
     tuberculin syringe may be used as well.

     (b) Holding the sieve in one hand, press the piece of paper
     carrying the stool firmly against the mesh. Careful
     positioning of the sample on the mesh will enable up to 25
     samples to be processed on one sieve, without danger of
     their mixing, before the sieve must be washed.

     (c) Using a clean applicator stick, scrape the sieved stool
     off the mesh surface.

     (d) Place the template in the middle of a clean slide.

@SubSlide[GlassFaec5-Text-]

     (e) Transfer the sieved stool (on the applicator stick) into
     the hole of the template and level off, avoiding any air
     bubbles.

     (f) Remove the template carefully, so that no stool is left
     in the hole of the template.

     (g) Upturn the slide onto another clean slide so as to make
     a sandwich with the stool in the middle.

     (h) With the slides remaining on the bench press down firmly
     with fingers or thumb to spread the sample in a slight
     rotating motion into an even, circular layer. (Experience
     will determine the amount of pressure needed; too much
     pressure breaks the eggs and may force the stool from
     between the slides; too little pressure leaves the sample
     too thick, making observation of the eggs more difficult).

     (i) Place the slides on the microscope stage with the grid
     on top, and examine at low power (x40) for eggs.

@SubSlide[GlassFaec6-Text-]
@Yellow[3.  Proper reading of slides and additional hints]

     (a) The slide can be examined immediately it has been
     prepared and should not be left for more than 4 hours, as
     air bubbles form and the edges tend to dry up. Use of the
     large slides delays the drying and avoids stool being
     squeezed out of the "sandwich".

     (b) Adjustment of the light source is important. Contrast
     and intensity of light should be altered to suit the stool
     sample being examined. In general dry samples require
     greater light intensity, wet samples a reduced aperture on
     the condenser.

     (c) Doubtful eggs can be confirmed by applying slight
     pressure to the upper slide while still in position on the
     microscope, This tends to roll the eggs over, thus revealing
     the spine clearly if it has been hidden.

@SubSlide[GlassFaec7-text-]

     (d) Viability of eggs may be checked by observation of flame
     cell movement. This can only be done using slightly thinner
     slides which enable the x100 objective to be used.

     (e) Other helminth eggs can be observed, but are more easily
     seen at x100 magnification. Hookworm eggs are best observed
     from day-old or older stools, where development of the
     larvae has passed the morula stage.

     (f) This technique is rapid. An experienced microscopist
     usually takes 2 minutes or less per slide. Preparation of 3
     slides per stool sample can compensate, to a degree, for the
     inability to store slides.

     (g) Provided stool samples remain moist, they can be
     processed and examined several days after collection.
     Refrigeration of stools prolongs storage time.

@SubSlide[GlassFaec8-Text-]

     (h) For quantitative work the consistency of the stool
     sample is important. Up to 10 times the number of eggs per
     gram of stool in samples taken on separate days from the
     same patient have been observed. Dry stools give high
     counts, and diarrhoeal stools give low counts, compared with
     stools of medium consistency from the same patient.

     (i) Stools should not be processed in any way before
     sieving. Addition of formalin is unnecessary, and makes the
     sample difficult to sieve; glycerine kills and clears the
     miracidia, making the eggs more difficult to see; the
     addition of iodine to the sieved stool after sieving and
     before the sandwich is made, does not increase sensitivity.

     (j) To wash sieves, soak for several hours in water to
     loosen the stool, and then clean using a high pressure jet
     of water from the tap on both sides of the screen. Dry
     before re-use. Scrubbing rapidly reduces the life span of a
     sieve. Two or three sieves used in rotation are appropriate.

@SubSlide[GlassFaec9-Text-]
@Yellow[4.  Suppliers]

The materials are the same as listed for the cellophane thick smear technique
(see Annex 2) except that glass slides are used instead of cellophane.

@SubSlide[SurvRxRec1-Text-]
@Yellow[Explanation for survey and treatment record]

SPECIMEN NUMBER:  All specimens submitted each day will be marked beginning
                  with the number 1 consecutively.
NAME:             The full name of the person will be recorded. The teacher or
                  parent should be requested to help with the recording of the
                  correct name.

SEX:              Male = 1 Female = 2

AGE:              Record the age at the last birthday. Children younger than
                  10 years of age will be recorded with a zero "0" in the
                  first column, i.e. 08 = 8 years old.

HISTORY:          The person who is registering the specimen will ask the
                  person:
                  1) If he has ever urinated blood in his entire life.
                  2) If he has urinated blood within the last six months.

                  The responses will be recorded as 0 = No and 1 = yes.

@SubSlide[SurvRxRec2-Text-]
@Yellow[Explanation for survey and treatment record]

VISUAL:

Liver size:       The liver edge palpated below the right costal margin in the
                  resting supine position is measured with a centimetre ruler.
                  If the liver edge is not palpable an "0" is recorded.
                  Otherwise liver size is recorded to the nearest whole
                  centimetre.

@SubSlide[SurvRxRec3-Text-]
@Yellow[Explanation for survey and treatment record]

VISUAL:

Spleen size:      The spleen edge palpated below the left anterior axillary
                  line is measured according to the Hackett scale.

                  0 = normal spleen, not palpable on deep inspiration.
                  1 = spleen palpable only on deep or at least more than
                  normal inspiration
                  2 = spleen palpable on normal breathing but not projected
                  below a horizontal line half-way below the costal margin and
                  the umbilicus measured along a line dropped vertically from
                  the left nipple.
                  3 = spleen with the lowest palpable point projected more
                  than halfway to the umbilicus but not below a line drawn
                  horizontally through it.
                  4 = spleen with the lowest palpable point below the
                  umbilical level but not projected more than half-way towards
                  a horizontal line through the symphysis pubis.
                  5 = spleen with lowest palpable point below the lower limit
                  of class 4.

@SubSlide[SurvRxRec4-Text-]
@Yellow[Explanation for survey and treatment record]

VISUAL:

Urine:            The person registering the specimen will look at the
                  specimen and record if the specimen is bloody or muddy
                  brown.

                  The result will be recorded as:
                  0 = normal
                  1 = bloody or muddy brown
                  Clear brown or dark yellow urine is to be considered normal.

@SubSlide[SurvRxRec5-Text-]
@Yellow[Explanation for survey and treatment record]

URINE EGG COUNT:  The microscopist will record all the results on a separate
                  form which indicates specimen number and the number of eggs
                  up to 50 eggs per 10 ml of urine.

                  On this form only the code number for the number of eggs
                  will be recorded.

STOOL EGG COUNT:  The microscopist will record all results on a separate form
                  which indicates the specimen number and the number of eggs
                  up to 33 eggs per slide. If more than 33 eggs are present,
                  the result is recorded as 34+. In all summary reports
                  persons with more than 33 eggs per slide will be reported as
                  having more than 800 eggs per gram of faeces.

@SubSlide[SurvRxRec6-Text-]
@Yellow[Explanation for survey and treatment record]

WEIGHT:           If the person is infected,he will be weighed and the weight
                  recorded.

TREATMENT:        If the person is treated with praziquantel this column will
                  be marked P. If the person was treated with metrifonate,
                  then each dose taken will be marked"l". A complete treatment
                  will be"111"- 3 doses given 2 weeks a part. If a dose was
                  missed "O" should be recorded.


@chapter[Treatment]
@Slide[MicroSc-PCX-]

@Window[This chapter discusses issues related to chemotherapy.
At the end of this chapter, you will know about
various drugs used to treat schistosomiasis, their
strengths and weaknesses, and their recommended regimen.]

@Slide[Rx1-Text-Prevalence-Transmission-Treatment regimen-]
@Yellow[1.  Introduction]

Interest in the chemotherapy of schistosomiasis has never been greater.
After 70 years' experience with chemotherapeutic agents, some of which were
toxic, the recent development of safe and effective oral drugs has awakened
general interest among those concerned with schistosomiasis control.
A strategy aimed at the direct and rapid control of disease is now feasible
in contrast to the slow reduction resulting from transmission control.

Nevertheless, in spite of the promise of these drugs, optimum treatment
regimens need to be established (i.e. who should be treated and how often)
to ensure the economical use of drugs for maximum cost benefit impact. The
long-term effects on the prevalence and intensity of infection and the
manifestations of disease in communities need to be clarified for
establishing optimum treatment schedules. Caution is necessary however
since the correct usage of these drugs must be learnt, their action on the
infection and the disease caused by Schistosoma observed and the short- and
long-term undesirable side effects understood. It must not be forgotten
that chemotherapy is a means to schistosomiasis control, not an end in
itself.

@Slide[Rx2-Text-Compliance rate-Dosage-Health education-PHC-Sanitation-Water suppply-]

The success of a chemotherapy programme will be enhanced by a well organized
health education and information effort prior to, during and after the
intervention. The community should understand that the available anti-
schistosomal drugs will not eradicate schistosomiasis. The role of the
population in contaminating their environment and the importance of
sanitation and water supply have to be emphasized. A high compliance rate
can be expected if the community is adequately informed in advance.

Whenever antischistosomal drugs are to be used, it is important:
(1) that the objectives to be achieved by the use of chemotherapy be
clearly defined; (2) that the most appropriate drug be chosen;
(3) that the correct dosage schedule be followed; (4) that adequate
information on the drug, its side effects and any contraindications be
widely available in the health delivery system; (5) that chemotherapy be
integrated into the primary health care system if necessary.

@SubSlide[ObjectRx-Text-Intensity of infection-Morbidity-S. haematobium-S. mansoni-]
@Yellow[2.  The objective of the use of chemotherapy in control programmes]

The primary objective of the use of specific chemotherapy in schistosomiasis
control programmes is reduction of human morbidity to levels below public
health importance. In general this goal will be achieved when all remaining
infections due to S. haematobium are below 50 eggs per 10 ml of a random
urine sample or when all remaining infections due to S. mansoni are below
100 eggs per gram of faeces. As the control efforts continue, other goals
related to prevalence and intensity of infection may be defined.

@SubSlide[EffectRx-Text-]
@Yellow[3.  Effect of chemotherapy on Schistosoma infection]

The current antischistosomal drugs (i.e. metrifonate, oxamniquine and
praziquantel) after administration to large populations have the following
sequential effects:

   (1)   elimination and cure of the infection is obtained in a
         high proportion of the infected population; and, in any
         event,

   (2)   the intensity of infection is reduced in those persons who
         remain infected;

   (3)   after elimination of the infection or reduction of the
         intensity of the infection, the level of contamination by
         those remaining infected is dramatically altered and
         reduced;

@SubSlide[EffectRx2-Text-]

   (continued)

   (4)   after this "chemotherapeutic shock" the risk of snail
         infection and transmission of schistosomiasis is lower,
         and

   (5)   the risk of development of severe disease, associated with
         heavy infections, is lower.

@SubSlide[EffectRx3-Text-]
@Yellow[4.  Effect of chemotherapy on morbidity caused by schistosoma infection]

The effects of currently available antischistosomal drugs on morbidity due
to schistosomiasis are now being frequently reported. The benefit of
treatment with older antischistosomal drugs in spite of their toxicity is
well documented in the scientific literature.

Single doses of praziquantel and different treatment regimens of metrifonate
rapidly reduce the frequency and degree of haematuria, proteinuria and
leukocyturia. In a recent study in an endemic area on Lake Volta, Ghana,
treatment of S. haematobium infection with praziquantel was shown to reduce
the prevalence of gross haematuria in children as well as adults by 91% and
77% respectively at six month follow-up. Furthermore, in both children
and adults, haematuria was reduced by more than 65% and proteinuria of
100 mg/100 ml of urine or more was reduced by over 70% as measured by
reagent strips. Other studies in Niger, Burkina Faso, Egypt and Tanzania
have shown similar results. Improvement of urinary tract disease, was
demonstrated by ultrasound and/or intravenous pyelography, after treatment
with praziquantel or metrifonate in different settings.

@SubSlide[EffectRx4-Text-]

The morbidity associated with of S. mansoni, S. japonicum, S. mekongi and
S. intercalatum infection may be reduced by appropriate treatment. Both
hepatomegaly and splenomegaly due to s. mansoni are reduced after treatment
with either praziquantel or oxamniquine. These manifestations due to
S. japonicum or S. mekongi are also reduced after treatment with
praziquantel. The risk of development of hepatosplenomegaly due to
schistosomiasis is reduced by antischistosomal treatment. Glomerulonephritis
associated with S. mansoni has been resolved with clinical improvement after
treatment with both oxamniquine and praziquantel. Cerebral lesions due to
S. japonicum have been successfully treated with praziquantel; central
nervous system (CNS) lesions in the acute phase of S. japonicum infection
may resolve spontaneously.

Prolonged Salmonella infections associated with S. mansoni infection have
been successfully treated with oxamniquine and praziquantel. This unusual
clinical syndrome is also associated with S. intercalatum and S. haematobium
infection but its treatment with the currently available antischistosomal
drugs has not been reported.

@SubSlide[CurrentRx-Text-]
@Yellow[5.  Current antischistosomal drugs]

      The ideal antischistosomal drug would fulfill the following
      criteria:

      (1)   be inexpensive;

      (2)   be well tolerated;

      (3)   be given without medical supervision;

      (4)   have a high and prolonged therapeutic index;

      (5)   remain chemically stable for long periods of time without
            requiring special storage conditions;

      (6)   not interact with other drugs, foodstuffs, alcohol or
            tobacco.

These above criteria could also be of value for assessing the appropriate
available drugs for use in a control programme.

@SubSlide[CurrentRx2-Text-]

The current antischistosomal drugs are listed in the WHO Model List of
Essential Drugs (Use of essential drugs, WHO Technical Report Series,
No. 685, p. 21, 1983). These drugs are not listed in the Model List of
Drugs for Primary Health Care (same report p. 43).

@SubSlide[Metrif-Text-]
@Yellow[5.1   Metrifonate] (Bilarcil(R))

Metrifonate is an organophosphorus compound used as a pesticide since 1952.
In 1962 this compound was discovered to have specific activity against
S. haematobium. Metrifonate is transformed in the mammalian host to
dichlorvos by a non-enzymatic process. Dichlorvos has specific
anticholinesterase activity. Neither the basis for the lack of activity
against S. mansoni nor the mode of action against S. haematobium is known.

The concentration of dichlorvos within both these species of Schistosoma is
the same after treatment of infected experimental animals with metrifonate.
There are only very slight recognized differences between the
cholinesterases of S. haematobium and S. mansoni. The absence of activity
against S. mansoni does not appear to be due either to biochemical
differences between the parasites or to differences in the concentration of
the active metabolites in the parasite.

@SubSlide[Metrif2-Text-]

The current hypothesis advanced to explain the preferential activity of
metrifonate against S. haematobium is based on the anatomical location of
the parasite in the inferior vena cava and the vesical venous plexus
contrasted to the location of S. mansoni in the portal mesenteric system.
Although displacement of S. haematobium adult worms to the lungs after
treatment with metrifonate has been observed experimentally, this has not
been confirmed by clinical observations in man. Thus the mode of action
of metrifonate remains unresolved.

@SubSlide[Metrif3-Text-]
@Yellow[5.1.1 Treatment] (Metrifonate)

The standard drug regimen is 7.5 - 10 mg/kg body weight given in three doses
at two week intervals (see Annex 2). This regimen has been extensively
evaluated in the field. Another suggested regimen using single 10 mg/kg
doses at intervals of six months or one year has not been sufficiently
evaluated in the field to provide meaningful comparisons with the customary
regimens.

@subslide[Metrif4-Text-]
@Yellow[5.1.2 Side effects]

It is remarkable that in spite of decrease in plasma and erythrocytic
cholinesterase after treatment with metrifonate, the clinical
manifestations are insignificant or non-existent. The level of plasma
cholinesterase returns to normal within two weeks. Erythrocyte levels take
longer to return to normal. Erythrocyte levels are more closely related to
brain levels than are plasma levels.

The side effects which may occur in persons treated with metrifonate are
the following: nausea/vomiting, colic, muscular weakness, dizziness,
sweating, fainting and rarely diarrhoea.

Atropine sulfate (1 mg every six hours) may be used to treat severe side
effects. In the rare event of severe cholinesterase depression, pralidoxine
iodide (2-PAM) may be useful to reduce clinical symptoms and restore enzyme
activity. This compound has rarely, if ever, been used. The drug is well
tolerated. Patients have survived overdoses of metrifonate up to 75 mg/kg
or ten times the recommended single oral dose.

@SubSlide[Metrif5-Text-]
@Yellow[5.1.3 Contraindications]

Agricultural workers who are exposed to organophosphorous compounds should
not be treated with metrifonate. Although there is no evidence of
embryotoxicity or teratogenicity of metrifonate in animal studies, the
treatment during pregnancy is not recommended. Interaction with other drugs
aside from synergism with other organophosphorus compounds is not known.

@Yellow[5.1.4 Therapeutic index]

The cure rates in schistosomiasis control programmes range from 40-65% with
a 90% reduction in egg counts in those who are not cured. Reduction in
hookworm egg counts may be observed.

@SubSlide[Oxam-Text-]
@Yellow[5.2    Oxamniquine] (Mansil(R) Vansil(R))

Oxamniquine is a tetrahydroquinoline compound effective only against
S. mansoni. After ingestion the drug is well absorbed and extensively
metabolized into active acidic metabolites which are excreted in the urine.
Only 0.4-1.9% of the oral dose is excreted as unchanged drug in the urine
and 41-73% is excreted as a 6-carboxy metabolite with traces of a
2-carboxylic acid fraction. Most of the metabolites are excreted in the
first 12 hours.

The adult S. mansoni male worms are more susceptible to oxamniquine than
the female worms. The precise mode of action is not known, however large
subtegumental blobs are formed associated with worm death. The early
developmental stages of S. mansoni are also susceptible to oxamniquine.

@SubSlide[Oxam2-Text-]
@Yellow[5.2.1 Treatment]

In Brazil and West Africa, S. mansoni infections in adults respond well to
15 mg/kg in a single oral dose which yields a 60-90% cure rate. Children
in these same areas require 20 mg/kg to achieve similar cure rates.

In Central and East Africa, the effective dose ranges from 30-45 mg/kg
while in Egypt doses of up to 60 mg/kg given over three days are required.

@SubSlide[Oxam3-Text-]
@Yellow[5.2.2 Side effects]

Oxamniquine is well tolerated especially if given after a meal. The most
frequent side effects have been dizziness, drowsiness and headaches. These
events occur 1-2 hours after ingestion and rarely last more than 6 hours.
Vomiting and diarrhoea are infrequent.

Hallucinations and psychic excitement following oxamniquine are known to
occur. Epileptiform convulsions may occur, though rarely, in persons with a
history of seizures (7 cases out of 5 million treatments).

Occasionally orange red discolouration of the urine has been observed after
treatment.

In Egypt after completion of a three day course of treatment, a fever
lasting 24-72 hours has been observed with a typical Loeffler syndrome.
This has not been observed elsewhere.

@SubSlide[Oxam4-Text-]
@Yellow[5.2.3 Contraindications]

Treatment of persons with a prior history of central nervous system disease
or severe liver disease should be conducted under medical supervision.
Treatment during pregnancy is not recommended. Interaction with other drugs
is not known.

@Yellow[5.2.4 Therapeutic index]

The cure rates in schistosomiasis control programmes range from 60-85% with
a reduction in egg counts of over 90% in those who are not cured at one year
after treatment. Cure rates are somewhat lower for children.

@SubSlide[Praz-Text-]
@yellow[5.3 Praziquantel] [BiltricideR)

Praziquantel is a heterocyclic pyrazino-isoquinoline compound that does not
resemble previous antischistosomal drugs. It is effective against S. mansoni,
S. haematobium, S. japonicum, S. mekongi and S. intercalatum. Praziquantel is
effective against most other trematodes and against cestodes. The mode of
action appears to be a direct effect on the tegument of the adult worm.

The drug is rapidly metabolized in man and little unchanged praziquantel is
excreted.  80% of the absorbed drug is excreted as metabolites within 24
hours, principally in the urine.

The pathology of schistosomiasis in animals receiving a curative dose of
praziquantel is characterized by a reduction in the cellular infiltrate
around the granuloma and a reduction in fibrosis in tissues with residual
Schistosoma eggs. These observations suggest that praziquantel has a direct
effect on the immunopathology related to the infection.

@SubSlide[Praz2-Text-]
@Yellow[5.3.1 Treatment]

Praziquantel is taken orally in single or divided doses. For S. mansoni and
S. haematobium infections, 40 mg/kg in a single dose is recommended. The
same dose is effective against combined S. mansoni and S. haematobium
infections. If feasible, split doses, given up to 6 hours apart, may
improve cure rates. For S. japonicum infection, 60 mg/kg in a split dose is
recommended.

@Yellow[5.3.2 Side effects]

Infrequently nausea, vomiting and mild to moderate epigastric discomfort or
pain occur within 8 hours after treatment. Mild headache, dizziness, and
drowsiness may also occur. Occasionally pruritus and slight urticaria have
been observed. All secondary effects subside completely within 48 hours of
treatment.

@SubSlide[Praz3-Text-]
@Yellow[5.3.3 Contraindications]

Treatment during pregnancy is not recommended. If treatment is required
while a mother is breast feeding, praziquantel may be excreted in breast
milk up to 24 hours after treatment. Interaction with other drugs is not
known.

@Yellow[5.3.4 Therapeutic index]

The cure rate for S. haematobium infection in field studies is 80-95% at
three months and about 80% at one year after treatment. The reduction in
egg counts in those who are not cured is usually 90-95% at one year. A
lower cure rate has been observed in combined S. mansoni and S. haematobium
infection in limited studies and requires further evaluation. The cure rate
and reduction of egg count in S. japonicum infection is similar to that
observed for S. haematobium.

@SubSlide[RxDel-Text-]
@Yellow[6.  Chemotherapy delivery systems]

The selection of a delivery system for antischistosomal chemotherapy should
be based on a sound understanding of the epidemiology of schistosomiasis as
well as the effectiveness of the drug. The basic elements of any
chemotherapy delivery system are personnel, diagnostic techniques and
associated materials, drugs, logistical support and data management.

@Yellow[6.1   Mass treatment]

Strictly speaking, this term refers to treatment of entire populations
without prior individual diagnosis. The decision to employ mass treatment
must be based on adequate epidemiological data indicating that a very high
proportion of the population is infected. The sampling frame and design of
this approach are critical and should be based on the smallest
administrative units.

Case detection costs are minimal and restricted to preliminary sampling to
establish the existence of a high prevalence; drug and delivery costs are
maximal but maximum effects on morbidity and transmission can be expected.

@SubSlide[RxDel2-Text-]
@Yellow[6.2   Selective population chemotherapy] (SPC)

In this approach, urine and/or stool specimens from the entire population of
an area are examined.  Only persons excreting Schistosoma eggs are treated.

Case detection costs are high but drug costs are less than with mass
treatment as only infected persons are treated.  Delivery costs may be lower
than with mass treatment.  A high level of morbidity control can be expected
and the effect on transmission will be only a little less than with mass
treatment if the diagnostic test used to identify infected persons is
sensitive.

@SubSlide[RxDel3-Text-]
@Yellow[6.3   Selected group treatment]

This approach is a variant of selective population chemotherapy. As peak
prevalence, intensity and morbidity are generally found in the younger age
groups, treatment can be given to these persons - either to all in the
group or to all those infected.

If a high proportion of children go to school, this approach is probably the
easiest to organize. When the whole group is treated, case detection costs
are limited to the survey defining the epidemiological status of the area;
and drug delivery costs will be less than in the regimes described above,
and, although the overall effect on morbidity and transmission will be less
than with mass therapy, it will be high in the age groups at greatest risk
and responsible for a high proportion of environmental contamination.

On the other hand, if only infected persons in the group are treated, case
detection costs increase but drug costs are less than when  all are treated.
These approaches probably have the greatest benefit relative to cost.

@SubSlide[RxDel4-Text-]
@Yellow[6.4   Targeted chemotherapy]

This term has been suggested to apply to of egg output and who are at
greatest risk of this approach reported reduction of morbidity the treatment
of individuals with high levels developing disease. A small field trial of
but this remains a theoretical approach which has been inadequately tested
on a large scale.

@Yellow[6.5   Phased treatment]

The SPC approach has been more frequently applied than others, but in
countries with prevalence varying from locality to locality a more flexible
approach may be required. Thus mass treatment in areas of very high
prevalence can be followed, when prevalence and intensity of infection have
been reduced, by selective population chemotherapy and subsequently
selective group treatment. This appears to provide for the most economical
use of drugs.

@Slide[RxDel5-Text-]

   ╔═══════════════════════════════════════════════════════════════╗
   ║                COMPARATIVE COSTS AND BENEFITS OF              ║
   ║              DIFFERENT CHEMOTHERAPY DELIVERY SYSTEMS          ║
   ╟────────────────────────────────────────┬──────────────────────╢
   ║                          Costs         │     Effects on       ║
   ║ Delivery   Case                        │                      ║
   ║ system     detection   Drug   Delivery │Morbidity Transmission║
   ╟────────────────────────────────────────┼──────────────────────╢
   ║ Mass         +         ++++    ++++    │   ++++        ++++   ║
   ║ treatment                              │                      ║
   ║                                        │                      ║
   ║ SPC         +++        +++      +++    │   +++         +++    ║
   ║                                        │                      ║
   ║ Selected group                         │                      ║
   ║ treatment                              │                      ║
   ║                                        │                      ║
   ║ (a) Total    +         +++      +++    │   +++         +++    ║
   ║                                        │                      ║
   ║ (b) Infected +++       ++       +++    │   +++         ++     ║
   ║                                        │                      ║
   ║ Targeted    ++++       +       ++++    │   ++          +      ║
   ╚════════════════════════════════════════╧══════════════════════╝

@SubSLide[RxSched-Text-]
@Yellow[7.  Treatment schedules]

During the period when only toxic antischistosomal compounds were available,
both Praziquantel and oxamniquine are usually given in single oral doses.
There is no justification to reduce the recommended dosages which have been
determined by adequate clinical trials. On the other hand, there is
indication that in some areas of Central and East Africa, the dosage of
oxamniquine for S. mansoni infection should be up to twice that required in
West Africa or in the New World. Furthermore, in Egypt and Sudan the dosage
required may be up to three or four times higher than that of the New World.
This information is derived from several small scale clinical trials and
should be reconfirmed in each endemic country where use of oxamniquine is
anticipated.

@SubSlide[RxSched2-Text-]

For metrifonate, it is recommended that it be given in three doses of
7.5 mg/kg at two week intervals. The 100 mg metrifonate tablets and the
product package insert instructions facilitate the administration of
metrifonate at 10 mg/kg. The cure rates and reduction in S. haematobium egg
counts are similar for both dose levels. In large-scale use, the amount of
drug required would be less if a dosage of 7.5 mg/kg rather than 10 mg/kg
could be more accurately and rapidly administered in the field.

Single dose regimens of metrifonate of 10 mg/kg or two doses of 7.5 mg/kg
given at intervals of 4, 6 or 12 months have been suggested. The published
results of clinical trials of these reduced doses of metrifonate are not
conclusive. Some degree of reduction of excretion of S. haematobium eggs
has been obtained in all reported trials. Single dose treatment appears to
have little or no effect in endemic areas where the overall intensity of
infection is high. At present single dose regimens cannot be recommended
for operational control programmes. However, clinical trials comparing
single dose to multiple dose metrifonate treatment under field conditions
are encouraged.

@SubSlide[RxSched3-Text-]

The three dose course of metrifonate may be administered by minimally
trained health workers under medical supervision. Thus, the multiple dose
regimen should not be a serious limitation to its applicability in most
endemic areas. The initial dose may be administered by the team undertaking
the diagnostic procedures. Subsequent doses may be given by other health
workers or minimally trained community personnel. Even so compliance rates
for a three dose course are usually low.

@SubSlide[RxEval-Text-]
@Yellow[8.  Evaluation of chemothearpy]
In another document on diagnostic techniques in schistosomiasis control
(WHO/SCHISTO/83.69) the importance of quantitative parasitological
techniques is emphasized. The cure rates with available antischistosomal
drugs are expected to be high. Prevalence rates at 6 months or one year
should be at least 40% below the pretreatment figures. If prevalence is not
reduced to this extent, then the intensity of infection, either in terms of
number of persons excreting more than 50 eggs per 10 ml of urine or more
than 100 eggs per gram of faeces, should be reduced (Annex 1). If the
intensity of infection is not notably changed, then the following should be
taken into consideration:

@SubSlide[RxEval2-Text-]

      (a)   Drug failure

      The antischistosomal drugs should be properly stored to
      avoid deterioration. Drugs in storage as well as those in the
      field should be checked periodically to assure that active drugs
      are being used. Metrifonate has a shelf life of 2 years under
      proper storage conditions. The shelf life of oxamniquine and
      praziquantel is at least that long. No drug should be used past
      the expiration date. Drugs should be stored in a cool dry storage
      area. Refrigeration is not necessary.

      (b)   Operational failure

      Effective supervision of the distribution and administration of
      the drug is necessary in all control programmes.  Supervision may
      include inspection, however the supervisor's primary task is to
      accompany and support the operational teams.  If specific
      objectives (i.e. population to be examined) are not set, then
      supervision and assessment of operations are difficult if not
      impossible.

@SubSlide[RxEval3-Text-]

      (c)   Lack of compliance

      If the community does not accept treatment, then the reasons
      should be identified and corrected and attempts made to promote
      cooperation.

      (d)   "Resistance" of the parasite to the drug

      Resistance of S. mansoni to oxamniquine has been observed in
      less than 1% of those treated. Resistance to treatment is not an
      "all or none" phenomenon. Treatment with oxamniquine will
      eliminate most if not all S. mansoni parasites. The parasites
      which remain after treatment may be resistant to repeated
      treatment with oxamniquine.

      No known human schistosomes are resistant to praziquantel.

      No strains of S. haematobium resistant to metrifonate have been
      identified.

@SubSlide[ReRx-Text-]
@Yellow[9.  Retreatment schedules]

A single treatment with an antischistosomal drug should never be expected
to achieve a permanent cure or to prevent reinfection. In general within
populations with a high prevalence (50%) and intensity of infection (this
level must be defined in each area by assessing the data at the time of
the first survey), a planned assessment of the treatment programme is
required after 6 months or 1 year. If it is foreseen that no reexamination
of the population or of a representative sample of it would be possible
within one year of a treatment programme in areas of high prevalence, then
the programme should be appropriately modified within the limits of
available personnel and resources to assure a reliable evaluation. If
experience in epidemiologically similar areas has shown that reexamination
and retreatment of positive cases is feasible and satisfactory at 18 months
or more, then a longer interval before retreatment may be justified.

@SubSlide[ReRx2-Text-]

Retreatment implies that reexamination of the target population is
necessary. The data from careful, continuous and systematic surveillance
in endemic areas will determine the appropriate reexamination and
retreatment schedules. Periodic examination of school age children, of
selected adult populations such as agricultural workers at high risk or
even of entire communities is in each case an optional approach.

The strategy of morbidity control anticipates that transmission will
continue after large-scale treatment but probably at a lower level than
before for some period. Further treatments will be required to maintain
control of morbidity. The rate at which prevalence and intensity of
infection increases depends on:

@SubSlide[ReRx3-Text-]

(a)   The number of persons remaining infected after treatment which is
      dependent on:

      (1)   the pre-treatment level of endemicity,

      (2)   the operational approach used;

      (3)   the level of population participation in respect of
            providing material for case detection and of accepting full
            courses of therapy;

      (4)   the "cure" rate;

      (5)   the numbers of deferred treatments due to pregnancy, ill
            health, etc.;

      (6)   the extent of population movement and immigration of
            infected persons.

@SubSlide[ReRx4-Text-]

(b)   The rate of reinfection which is dependent on:

      (1)   the extent of water contact which may be inversely
            proportional to the availability of a safe, adequate
            and reliable water supply;

      (2)   the extent of faecal and/or urine contamination in the
            environment;

      (3)   the extent of snail intermediate host populations and the
            seasonality of transmission;

      (4)   in areas where S. mansoni and S. japonicum is endemic, the
            rates of infection among animal reservoirs as these may be of
            epidemiological significance to maintain transmission.


The availability of diagnosis and treatment in the first level health
delivery system would support intensive control efforts and will be
essential during the maintenance phase of schistosomiasis control.

@SubSlide[CostRx-Text-]
@Yellow[10.  Cost of treatment]

Although there is great interest in the antischistosomal drugs, there is
also concern about their cost for large-scale use. Cost estimates should be
weighted in favour of treatment of children, who are the major portion of
the infected population. The cost of these drugs is calculated on the basis
of actual large volume direct purchases by national schistosomiasis control
programmes. The costs of antischistosomal drugs will vary from one country
to another. Current prices must be confirmed from local and international
suppliers and the manufacturer.

@SubSlide[CostRx2-Text-]

In most control programmes, in which the costs of operations have been
carefully analyzed, the cost of the drug comprises 10-30% of the total
cost of delivery. The cost of the drug usually represents a hard currency
cost to the endemic country which may be restricted. The World Health
Organization and the manufacturer of praziquantel have made a unique
agreement concerning a special low price for the drug when it is used in
large-scale national control programmes and this agreement has been
extended to other United Nations agencies. The cost of the drug however
should not be the ultimate factor to determine its proper use. If funds
are restricted it may be appropriate to limit control operations to smaller
geographical areas or affected communities rather than attempting to use
the drug indiscriminately over a large area.

As current antischistosomal drugs become available at a lower cost, it will
be important that the endemic countries be prepared to use these drugs on a
large scale.

@SubSLide[OtherRx-Text]
@Yellow[11.  Other practical considerations]

Among other observations regarding chemotherapy, it is important to
emphasize the following:

(a)   The community as a whole and each individual treated must always
      be informed about the possible side effects so that unexpected
      reactions by the population may be avoided.

(b)   In large-scale programmes the tablets (metrifonate and praziquantel)
      should be broken before treatment begins. The metrifonate tablets can
      be broken in halves (50 mg each) and quarters (25 mg each). The
      praziquantel tablets of 600 mg may be broken in halves (300 mg) and
      quarters (150 mg) and simple tables should be made so that the person
      administering the drug can give the proper dose.

@SubSlide[OtherRx2-text-]

(c)   It is not sufficient to ask the patient if he has swallowed the pills.
      The field personnel must inspect the mouth to assure complete
      ingestion of the pills. This observation may make the difference
      between cure and treatment failure.

(d)   The compliance of the population during large-scale treatment is an
      important measure of the acceptability of a drug and the success of
      health education.


@SubSlide[DataRx-Text-]
@Yellow[12.  Presentation of data on chemotherapy]

The presentation of data on chemotherapy in control programmes should be
easily understood. The rapid evaluation of results will ensure efficient
and rational modifications of the operations and operational schedules.
Two general types of data are available: (1) the most common situation:
data from whole populations before and after treatment in which the data
from individuals cannot be matched; (2) an infrequent situation: data
available from the same persons before and after treatment.

The examples given in this section are theoretical. Two general types of
data may be available:

1.    Data from whole populations before and after treatment in which
      the data from individuals cannot be matched.

In this situation it is not possible to know if an individual has been
examined before and after treatment. Some persons seen before treatment may
not be examined after treatment or vice versa. The data may be simply
presented as follows:

@SubSlide[DataRx1-Text-]
@Yellow[1.1   Prevalence]

      Status            Before            After

      Negative          (a) 1000          (c) 1800

      Positive          (b) 1500          (d)  600

      Total             (e) 2500          (f) 2400

Prevalence before treatment: b/e (%) 1500/2500 = 60%

Prevalence after treatment:  d/f (%)  600/2400 = 25%

Reduction in prevalence: b/e(%) - d/f(%)  60% - 25% = 35% = 58.3%
                         ───────────────  ─────────  ────
                              b/e(%)          60%     60%   reduction

The letters (a, b etc. ) used here and elsewhere in this annex are only
intended as a guide for explanation and have no specific meaning outside
the example.

@SubSlide[DataRx2-Text-]

Since the number of persons examined before treatment will usually be
different from the number of persons examined after treatment, the reasons
for these differences should be explained in the evaluation of the data.
Large differences between the total examined before treatment and after
treatment may be due to operational problems which could be corrected.

@Yellow[1.2   Intensity of infection]

Measurement of the intensity of infection is an important criteria for
evaluating the effectiveness of treatment.

@SubSlide[DataRx3-Text-]
@Yellow[1.2.1  S. haematobium infection: eggs per 10 ml of urine]

      Eggs/10 ml        Before treatment        After treatment

      0                 (a)   1000              (c)   1800
      1-49              (W)   1000              (X)    550
      50+               (y)    500              (Z)     50
      Total             (e)   2500              (f)   2400

Prevalence of heavily inf. before treatment = y/e(%) 500/2500 = 20%
Prevalence of heavily inf. after treatment = z/f(%) 50/2400 = 2.1%
Reduction in prevalence of heavily inf.: (y/e(%) - z/f) (20% - 2.1%)
                                         ────────────── ────────────
                                             y/e(%)          20%

                                          = 89.5% reduction

NOTE: Compare the tables in 1.1 and 1.2.1, observe that a, c, e, f
are the same numbers:
      (In 1.2.1   w + y =     b     (in 1.1)
      (In 1.2.1   x + z =     d     (in 1.1)

@SubSlide[DataRx4-Text-]
@Yellow[1.2.2  S. mansoni infection: eggs per gram faeces (eggs per slide)]

      The Kato-Katz cellophane faecal thick smear technique is used.
The suggested egg count classes which may be modified according to
national standards, are:

            Eggs per slide          Eggs per gram

                  1-4         =         24 - 96
                  5-33        =        120 - 792
                  34+         =           816+

@SubSlide[DataRx5-Text-]

              Eggs per              Before            After
            Kato-Katz slide         treatment         treatment

                  0                 (a)1000           (c) 1800
                  1-4               (q)1000           (t)  500
                  5-33              (r) 400           (u)   90
                  34+               (s) 100           (v)   10
                  Total             (e)2500           (f) 2400

Prevalence of heavily inf. before treatment = s/e(%) 100/2500 = 4%
Prevalence of heavily inf. after treatment = v/f(%) 10/2400 = 0.4%
Reduction in prevalence of heavily inf. = (s/e(%)-v/f(%)) (4%-0.4%)
                                          ─────────────── ─────────
                                                s/e(%)       40%

                                          = 90% reduction

NOTE: It is also possible to calculate the prevalence and reduction
of light infections (1 - 4 eggs).

@SubSlide[DataRx6-Text-]
@Yellow[2.  Data available from the same persons before and after treatment]

@Yellow[2.1 Status of the population before and after treatment:]

      Each person was examined before and after treatment.  In this
table some persons may have received treatment others may not.  The
examination after treatment may be done 6 months or one year later.

@SubSlide[DataRx7-Text-]

                                      Before treatment

                        Negative          Positive          Total

After treatment

Negative                (g)  990             (i)            (k)  8990
Positive                (l)   10             (j)            (e)  1010
Total                   (m) 1000             (n)            (o) 10000


Prevalence before treatment:        n/o   9000/10000        =     90%
Prevalence after treatment          e/o   1010/10000        =     10.1%

Reduction in prevalence       n/o - e/o    90% - 10% = 88.7% reduction
                              ─────────    ─────────
                                 n/o          90%

@SubSlide[DataRx8-Text-]

Conversion rate (negative to positive) = 1/m  10/1000 = 1%
Negative rate* = i/n  8000/9000 = 88.9%

      *Also termed "apparent cure rate". This figure is the
      cumulative effect of treatment and transmission.

Since the same persons are examined before and after treatment
the total of m + n should always equal k + e. If these numbers do
not agree, then the data should be checked. If a person was not
examined after treatment, his data are incomplete and should not be
included in this calculation.

@SubSlide[DataRx9-Text-]
@Yellow[2.2   Status of the population before and after treatment: ]

                 treated versus not treated

In a selective population chemotherapy (SPC) approach all persons who are
negative at the first examination will not be treated. Some of these
"negative" persons may be lightly infected and on the second examination
their parasitological examination may be positive.

@SubSlide[DataRx10-Text-]
@Yellow[2.2.1 Persons treated]

            After treatment               Before treatment
                                              Positive

               Negative                      (p) 8000

               Positive                      (q)  100

               Total                         (r) 8100

               Negative rate = p/r  8000/8100 = 98.8%

@SubSlide[DataRx11-Text-]
@Yellow[2.2.2 Persons not treated]

Usually persons who are not infected will not receive treatment.  Sometimes
persons may be ineligible for treatment due to contraindications, e.g.
pregnancy, chronic disease.  The data from the same persons who were not
treated may be analyzed.

      After treatment                     Before treatment

                                    Negative    Positive    Total

      Negative                      (g)  990    (s)  50     (u) 1040

      Positive                      (h)   10    (t) 850     (v)  860

      Total                         (m) 1000    (w) 900     (x) 1900

Reversion rate (positive to negative) = s/w   50/900 = 5.6%

NOTE: In comparing the tables in sections 2 and 3, observe that o = r+x
@SubSlide[DataRx12-Text-]

Exercises in preparing data from large scale treatment
programmes are available in the following documents:

      PDP/83.11               Examples of presentation of survey data

      PDP/83.12               Completed exercises on presentation of survey
                              data to accompany PDP/83.11

      WHO/SCHISTO/85.81       Statistical methods applicable to
      WHO/ESM/85.1            schistosomiasis control programmes by H.
                              Dixon


@Slide[DosageMF-Text-]

╔═════════════════════════════════════════════════════════════════════════╗
║                      Dosage schedule: metrifonate                       ║
║                     7.5 mg/kg body weight per dose                      ║
╟─────────────────────────────────────────────────────────────────────────╢
║     Weight range       Dose range        No. tablets       Actual dose  ║
║           (kg)           (mg)                                 (mg)      ║
╟─────────────────────────────────────────────────────────────────────────╢
║     6     -     7  │   45   -  52.5  │       1/2           │     50     ║
║     8     -     11 │   60   -  82.5  │    1/2 + 1/4        │     75     ║
║     12    -     14 │   90   - 105    │        1            │    100     ║
║     15    -     17 │  112.5 - 127.5  │      1 + 1/4        │    125     ║
║     18    -     21 │  135   - 157.5  │      1 + 1/2        │    150     ║
║     22    -     24 │  165   - 180    │   1 + 1/2 + 1/4     │    175     ║
║     25    -     27 │  187.5 - 202.5  │        2            │    200     ║
║     28    -     31 │  209.5 - 232.5  │      2 + 1/4        │    225     ║
║     32    -     34 │  240   - 255    │      2 + 1/2        │    250     ║
║     35    -     37 │  262.5 - 277.5  │   2 + 1/2 + 1/4     │    275     ║
║     38    -     41 │  285   - 307.5  │        3            │    300     ║
║     42    -     44 │  315   - 330    │      3 + 1/4        │    325     ║
║     45    -     47 │  337.5 - 352.5  │      3 + 1/2        │    350     ║
║     48    -     51 │  360   - 382.5  │   3 + 1/2 + 1/4     │    375     ║
║     52    -     54 │  390   - 405    │        4            │    400     ║
║     55    -     57 │  412.5 - 427.5  │      4 + 1/4        │    425     ║
║     58    -     61 │  435   - 457.5  │      4 + 1/2        │    450     ║
║     62    -     64 │  465   - 480    │   4 + 1/2 + 1/4     │    475     ║
║     65    -     67 │  487.5 - 502.5  │        5            │    500     ║
║     68    -     71 │  510   - 532.5  │      5 + 1/4        │    525     ║
║     72    -     74 │  540   - 555    │      5 + 1/2        │    550     ║
║     75    -     77 │  662.5 - 577.5  │   5 + 1/2 + 1/4     │    575     ║
║     78    -     81 │  585   - 607.5  │        6            │    600     ║
║     82    -     84 │  615   - 630    │      6 + 1/4        │    625     ║
║     85    -     87 │  637.5 - 652.5  │      6 + 1/2        │    650     ║
╚═════════════════════════════════════════════════════════════════════════╝
@Slide[DosagePQ-Text-]
╔═════════════════════════════════════════════════════════════════════════╗
║                       Dosage schedule: praziquantel                     ║
║                   40 mg/kg body weight in a single dose                 ║
╟─────────────────────────────────────────────────────────────────────────╢
║      Weight range       Dose range        No. tablets       Actual dose ║
║          (kg)              (mg)                                  (mg)   ║
╟────────────────────┬───────────────────┬───────────────────┬────────────╢
║    10    -     12  │  400   -     480  │  1/2  +   1/4     │      450   ║
║    13    -     16  │  520   -     640  │       1           │      600   ║
║    17    -     19  │  680   -     760  │   1   +   1/4     │      750   ║
║    20    -     23  │  800   -     920  │   1   +   1/2     │      900   ║
║    24    -     27  │  960   -     1080 │ 1  + 1/2 + 1/4    │     1050   ║
║    28    -     31  │  1120  -     1240 │       2           │     1200   ║
║    32    -     34  │  1280  -     1360 │    2  + 1/4       │     1350   ║
║    35    -     38  │  1400  -     1520 │    2  + 1/2       │     1500   ║
║    39    -     42  │  1560  -     1680 │ 2  + 1/2 + 1/4    │     1650   ║
║    43    -     46  │  1720  -     1840 │       3           │     1800   ║
║    47    -     49  │  1880  -     1960 │    3  + 1/4       │     1950   ║
║    50    -     53  │  2000  -     2120 │    3  + 1/2       │     2100   ║
║    54    -     57  │  2160  -     2280 │ 3  + 1/2 + 1/4    │     2250   ║
║    48    -     61  │  2320  -     2440 │       4           │     2400   ║
║    62    -     64  │  2480  -     2560 │    4  + 1/4       │     2550   ║
║    65    -     68  │  2600  -     2720 │    4  + 1/2       │     2700   ║
║    69    -     72  │  2760  -     2880 │ 4  + 1/2 + 1/4    │     2850   ║
║    73    -     76  │  2920  -     3040 │       5           │     3000   ║
║    77    .     79  │  3080  -     3160 │    5  + 1/4       │     3150   ║
║    80    -     83  │  3200  -     3320 │    5  + 1/2       │     3300   ║
║    84    -     87  │  3360  -     3480 │ 5  + 1/2 + 1/4    │     3450   ║
║    88    -     91  │  3520  -     3640 │       6           │     3600   ║
╚════════════════════╧═══════════════════╧═══════════════════╧════════════╝

@SubSlide[OptionalRx-Text-]
@Yellow[Optional chemotherapy approaches]

@Window[The following approaches are suggested according to the prevalence of
schistosomiasis among 7-14 (school age) year old children and type of
schistosomiasis in the locality under consideration for intervention.]

                  1. Attack phase - intervention phase

Risk        Prevalence of           Type of
            infection*              infection               Treatment

High            > 50%               S. haematobium    All school age children

                                    S. mansoni        All survey population
                                    S. japonicum

Moderate    25%-50%                 S. haematobium    Only children aged 7-14
                                                      years old

                                    S. mansoni        All children aged 2-14
                                    S. japonicum      years

Low            < 25%                S. haematobium    Infected persons only
                                    S. mansoni        through health
                                    S. japonicum      delivery system

      * Index 7-14 years old children.

@SubSlide[OptionalRx2-Text-]
@Yellow[2. Maintenance]

      Sample prev of
      infection at      % of heavily
      follow up         infected persons        Treatment

                        High  > 25%
                        S.h.              S.h. - all school age children
                        S.m./S.j.         S.m./S.j. - entire population

HIGH     > 50%          Low   < 25%
                        S.h.              S.h. - only 7-14 year-old children
                        S.m./S.j.         S.m./S.j. - all children 2-14
                                          years of age

                        High  > 20%
                        S.h.              S.h. - only 7-14 year old children

                        S.m./S.j.         S.m./S.j - all children 2-14 years
                                          of age

@SubSlide[OptionalRx3-Text-]

MODERATE    25%-50%     Low   < 20%
                        S.h.              S.h. - only 7-14 year-old children
                        S.m./S.j.         S.m./S.j. - all children 2-14
                                          years of age after primary Rx

                        High  > 15%
                        S.h.              S.h. - PHC at yearly intervals
                        S.m./S.j.         S.m./S.j. - PHC at yearly intervals

LOW         < 25%       Low   < 15%
                        S.h.              S.h. - PHC at yearly intervals
                        S.m./S.j.         S.m./S.j. - PHC at yearly intervals

Key: S.h.  Schistosoma haematobium
     S.j.  Schistosoma japonicum
     S.m.  Schistosoma mansoni
     PHC   Primary Health Care

@SubSlide[OptionalRx4-Text-]
@Yellow[3.  Heavily infected persons]

      S. haematobium          >  50 eggs/10 ml of urine

      S. mansoni*             > 100-800 eggs/g of faeces

      S. intercalatum*        > 100 eggs/g of faeces

      S. japonicum*           > 100-800 eggs/g of faeces

      S. mekongi*             > 100 eggs/g of faeces

      * The definition of heavy infection is area-specific and may
vary from 100-800 eggs per gram of faeces.

@SubSlide[RxBib-Text-]
@Yellow[11.  Bibliography]

An asterisk (*) indicates specialized literature on the toxicology of the
antischistosomal drug.

@LightCyan[General]

Davis, A. Available chemotherapeutic tools for control of
schistosomiasis. Behring Institut Mitterlungen, 71: 90-103 (1982)

Mott, K.E. Control of schistosomiasis: morbidity reduction and
chemotherapy. Acta Leidensia, 49: 101-Ill (1982)

Nash, T.E., Cheever, A.W., Ottesen, E.A. & Cook, J.A. Schistosome
infections in humans: perspectives and recent findings. Annals of
internal medicine, 97: 740-754 (1982)

@SubSlide[RxBib2-Text-]
@LightCyan[Metrifonate]

Arap Siongok, T.K., Ouma, J.H., Houser, H.B. L Warren, K.S.
Quantification of infection with Schistosoma haematobium in relation
to epidemiology and selective population chemotherapy. II. Mass
treatment with a single oral dose of metrifonate. Journal of
infectious diseases, 138: 856-858 (1978)

Browning, M.D., Narooz, S.I., Strickland, G.Y., El-Masry, N.A. &
Abdel-Wahab, M.F. Clinical characteristics and response to therapy in
Egyptian children infected with Schistosoma haematobium. Journal of
infectious diseases, 149: 998-1004 (1984)

Davis, A. & Bailey, D.R. Metrifonate in urinary schistosomiasis.
Bulletin of the World Health Organization, 41: 209-224 (1969)

Diallo, S. & Druilhe, P. Activité du metrifonate sur les souches
sénégalaises de S. haematobium. Bulletin de la Société médicale
d'Afrique noire de Langue française, 18: 574-580 (1973)

@SubSlide[RxBib3-Text-]
@LightCyan[Metrifonate]

Diallo, S., Ceccon, J.-F., Victorius, A., Diouf, F. & N'Dir, O.
Efficacité de 3 cures de métrifonate dans le traitement de la
bilharziose urinaire au Sénégal. Dakar médical, 28: 67-76 (1983)

Doehring, E., Feldmeier, H., Dafalla, A.A., Ehrich, J.H.H., Vester,
U. & Poggensee, U. Intermittent chemotherapy with trichlorfon
(metrifonate) reverses proteinuria, haematuria and leucocyturia in
urinary schistosomiasis: results of a three year field study. Journal
of infectious diseases, 149: 615-620 (1984)

Druilhe, P., Bourdillon, F., Froment, A. & Kyelem, J.M. Essai de
contrôl de la bilharziose urinaire par trois cures annuelles de
métrifonate. Annales de la Société belge de Médicine tropicale, 61:
99-109 (1981)

Ejezie, G.C. & Ade-Serrano, M.A. Single dose treatment in urinary
schistosomiasis. Nigerian journal of parasitology, 1: 49-54 (1980)

@SubSlide[RxBib4-Text-]
@LightCyan[Metrifonate]

El Kholy, A., Boutros, S., Tamara, F., Warren, K.S. & Mahmoud, A.A.F.
The effect of a single dose of metrifonate on Schistosoma haematobium
infection in Egyptian school children. American journal of tropical
medicine and hygiene, 33: 1170-1172 (1984)

Gentilini, M., Danis, M., Houenassou, P., & Arnaud, J.P. Résultats de
l'activité schistosomicide d'un organophosphore, le métrifonate dans
la bilharziose urinaire. Bulletin de la Société de Pathologie
exotique, 66: 299-306 (1973)

Jewsbury, J.N., Cooke, M.J. & Weber, M.C. Field trial of metrifonate
in the treatment and prevention of schistosomiasis infection in man.
Annals of tropical medicine and parasitology, 71: 67-83 (1977)

Holmstedt, B., Nordgren, I., Sandoz, M. & Sundwall, A. Metrifonate.
Summary of toxicological and pharmacological information available.
Archives of toxicology, 41: 3-29 (1978)(*)

@SubSlide[RxBib5-Text-]
@LightCyan[Metrifonate]

Mason, P.R. & Tswana, S.A. Single dose metrifonate for the treatment
of Schistosoma haematobium infection in an endemic area of Zimbabwe.
American journal of tropical medicine and hygiene, 33: 599-601 (1984)

Metrifonate and dichlorvos: theoretical practical aspects.
Proceedings of a symposium held at the Royal Academy of Sciences in
Stockholm, November 3-4, 1980. Acta pharmacologica et toxicologica,
49: (Suppl. V): 1-137 (1981)(*)

Omer, A.H.S. & Teesdale, C.H. Metrifonate trial in the treatment of
various presentations of Schistosoma haematobium and S. mansoni
infections in the Sudan. Annals of tropical medicine and
parasitology, 72: 145-150 (1978)

Onadeko, M.0. Preliminary report on long term cure of schistosomiasis
using metrifonate (Bilarcil/Dipterex) - a new antischistosomal drug.
West African journal of pharmacology and drug research (Ikeja,
Nigeria), 5: 19-24 (1979)

@SubSlide[RxBib6-Text-]
@LightCyan[Metrifonate]

Pugh, R.N.H. & Teesdale, C.H. Single-dose oral treatment in urinary
schistosomiasis: a double blind trial. British medical journal, i:
419-432 (1983)

Pugh, R.N.H. & Teesdale, C.H. Long term efficacy of single dose oral
treatment in schistosomiasis haematobium. Transactions of the Royal
Society of Tropical Medicine and Hygiene, 78: 55-59 (1984)

Reddy, S., Oomen, J.M.V. & Bell, D.R. Metrifonate in urinary
schistosomiasis: a field trial in Northern Nigeria. Annals of
tropical medicine and parasitology, 69: 73-76 (1975)

Rey, J.L., Nouhov, H. & Sellin, B. Comparaison de trois posologies de
métrifonate en chimiothérapie de masse contre Schistosoma
haematobium. Médecine tropicale, 44: 57-60 (1984)

Rugemalila, J.B. & Eyakuze, V.M. Use of metrifonate for selective
population chemotherapy against urinary schistosomiasis in an endemic
area at Mwanza, Tanzania. East African medical journal, 58: 37-43
(1981)

@SubSlide[RxBib7-Text-]
@LightCyan[Metrifonate]

Stephenson, L.S., Latham, M.C., Kinoti, S.N. & Oduori, M.L.
Sensitivity and specificity of reagent strips in screening Kenyan
children for Schistosoma haematobium infection. American journal of
tropical medicine and hygiene, 33: 862-871 (1984)

Wilkins, H.A. & Moore, P.J. Single dose of metrifonate. Tropical
Medicine and Hygiene, 74: 692 (1980)

@SubSlide[RxBib8-Text-]
@LightCyan[Oxamniquine]

Araujo, N., Katz, N., Dias, E.P. & Souza, C.P. Susceptibility to
chemotherapeutic agents of strains of Schistosoma mansoni isolated
from treated and untreated patients. American journal of tropical
medicine and hygiene, 29: 890-894 (1980)

Bina, J.C. & Prata, A. Tratamento de esquistossomose com oxamniquine
(xarope) em crianças. Revista da Sociedade brasileira de Medicina
tropical, 9: 175-178 (1975)

Boudin, C., Moreau, J.-P. & Dupouy-Camet, J. Tentative d'interruption
de la transmission de Schistosoma mansoni dans une communauté rurale
de Haute Volta, par chimiothérapie de masse a l'oxamniquine en trois
cures bimestrielles. Cahiers ORSTOM, série entomologie médicale et
parasitologie, 20: 69-75 (1982)

@SubSlide[RxBib9-Text-]
@LightCyan[Oxamniquine]

Cunha, A.S. A avaliacao terapeutiçà da oxamniquine na esquistossomose
mansoni humana pelo metodo do oograma por biopsia de mucosa retal.
Revista do Instituto de Medicina tropical de Sao Paulo, 24: 88-94
(1982)

Efthimiou, J. & Denning, D. Spinal cord disease due to Schistosoma
mansoni successfully treated with oxamniquine. British medical
journal, 288: 1343-1344 (1984)

Guimaraes, R.X., Tchakerian, A., Dias L.C.S., Almeid, F.M.R. de,
Vilela, M.P., Cabeça, M. & Takeda, A.K. Resistência ao hycanthone e
oxamniquine em doentes com esquistossomose forma clínica
hepatointestinal. Revisea da Associaçao Medica brasileira, 25: 48-50
(1979)

Ibrahim, A.M.A. Evaluation of oxamniquine in the treatment of S.
mansoni infection among Sudanese patients. The East African medical
journal, 57: 566-573 (1980)

@SubSlide[RxBib10-Text-]
@LightCyan[Oxamniquine]

Kapend'a, K., Odio, W., Toko, A.L., Vandepitte, J., Kayembe, N. N. &
Wane, J. L'oxamniquine dans le traitement de l'infection à
Schistosoma mansoni. Annales de la Société belge de Médecine
tropicale, 62: 213-219 (1982)

Kilpatrick, M.E., Farid, Z., Bassily, S., El-Masry, N.A., Trabolsi,
B. & Watter, R.H. treatment of schistosomiasis mansoni with
oxamniquine - five years experience. American journal of tropical
medicine and hygiene, 30: 1219-1222 (1981)

Lambertucci, J.R., Greco, D.B., Pedroso, E.R.P., Rocha, M. O. da C.,
Salazar, H. M. & Lima, D. P. de. A double blind trial with
oxamniquine in chronic schistosomiasis mansoni. Transactions of the
Royal Society of Tropical Medicine and Hygiene, 76: 751-755 (1982)

Nozais, J.-P., & Geunier, M. Etude de l'efficacité de I'UK 4271
(oxamniquine, Pfizer) dans la bilharziose à Schistosoma mansoni en Afrique
de l'Ouest (étude parasitologique et sérologique portant sur 252 enfants).
Bulletin de la Société de Pathologie exotique, 72: 153-164 (1979)

@SubSlide[RxBib11-Text-]
@LightCyan[Oxamniquine]

Omer, A.H.S. Oxamniquine for treating Schistosoma mansoni infection
in Sudan. British medical journal, 2: 163-165 (1978)

Ott, B.R., Libbey, N.P., Ryter, R.J. & Trebbin, W.M. Treatment of
schistosome-induced glomerulonephritis. Archives of internal
medicine, 143: 1477-1479 (1983)

Prata, A., Bina, J.C., Barreto, A.C. & Alecrim M.G. Attempt to
control the schistosomiasis transmission by oxamniquine in an
hyperendemic locality. Revista do Instituto Medicina tropical de Sao
Paulo, 22 (Suppl 4)(1): 65-72 (1980)

Sleigh, A.C., Mott, K.E., Franca Silva, J.T., Muniz, T.M., Mota,
E.A., Barreto, M.L., Hoff, R., Maguire, J.H., Lehman, J.S. &
Sherlock, I. A three year follow-up of chemotherapy with oxamniquine
in a Brazilian community with endemic schistosomiasis mansoni.
Transactions of the Royal Society of Tropical Medicine and Hygiene,
75: 234-238 (1981)

@SubSlide[RxBib12-Text-]
@LightCyan[Praziquantel]

Andrews, P., Thomas, H., Pohlke, R. & Seubert, J. Praziquantel.
Medicinal research reviews, 3: 147-200 (1983)

Anonymous. Praziquantel. The medical letter, 24: (624): 108-109
(1982)

Bartsch, H., Kuroki, T., Malaveille, C., & Loprieno, N. Absence of
mutagenicity of praziquantel, a new effective antischistosomal drug
in bacteria, yeasts, insects, and mammalian cells. Mutation research,
58: 133-142 (1978)(*)

de Carvalho, S.A., Amato Neto, V., Zeitune, J.M.R., Goldbaum, M.,
Castilho, E.A. & Grossman, R.M. Availaçào terapêutica do praziquantel
(EMBAY 8440) na infecçào humana pelo S. mansoni. Revista do Instituto
de Medicina tropical de Sao Paulo, 26: 51-59 (1984)

@SubSlide[RxBib13-Text-]
@LightCyan[Praziquantel]

Coutinho, A., Domingues, A.L.C., Neves, J. & Almeida, S.T. Treatment
of hepatosplenic schistosomiasis mansoni with praziquantel.
Arzneimettel Forschung (Drug research), 33: 787-791 (1983)

Coutinho, A.-D., Domingues, A.L.C., Florencio, J.N. & Almeida, S.T.
Tratamento da esquistossomose mansonica hepatosplenica com
praziquantel. Revista do Instituto de Medicina tropical de Sao Paulo,
26: 38-50 (1984)

Davis, A. & Wegner, D.H.G. Multicentre trials of praziquantel in
human schistosomiasis: design and techniques. Bulletin of the World
Health Organization, 57: 767-771 (1979)

Davis, A.,Biles, J.E. & Ulrich, A.-M. Initial experiences with
praziquantel in the treatment of human infections due to Schistosoma
haematobium. Bulletin of the World Health Organization, 57: 773-779
(1979)

@SubSlide[RxBib14-Text-]
@LightCyan[Praziquantel]

Keittivuti, B., Keittivuti, A., O'Rourke, T. & D'Agnes, T. Treatment
of Schistosoma mekongi with praziquantel in Cambodian refugees in
holding centres in Prachinburi Province, Thailand. Transactions of
the Royal Society of Tropical Medicine and Hygiene, 78: 477-479
(1984)

Larouze, B. Un nouvel antibilharzien, le praziquantel (Biltricide).
Médecine d'Afrique noire, 28: 13-15 (1981)

McMahon, J.E. & Kolstrup, N. Praziquantel: a new schistosomicide
against Schistosoma haematobium. British medical journal, 2:
1396-1399 (1979)

Pearson, R.D. & Guerrant, R.L. Praziquantel: a major advance in
anthelminthic therapy.  Annals of internal medicine, 99: 195-198
(1983)

Review of preclinical and clinical trials. Arzneimittel Forschung
(Drug research), 31(I) 3a:  535-618 (1981)(*)

@SubSlide[RxBib15-Text-]
@LightCyan[Praziquantel]

Schutte, C.H.J., Osman, Y., van Deventer, J.M.G. & Mosese, G.
Effectiveness of praziquantel against the South African strains of
Schistosoma haematobium and Schistosoma mansoni. South African
medical journal, 64: 7-10 (1983)

de Souza Dias, L.C., Pedro, R. de J., & Deberaldini, E.R. Use of
praziquantel in patients with schistosomiasis mansoni previously
treated with oxamniquine and/or hycanthone: resistance of Schistosoma
mansoni to schistosomicidal agents. Transactions of the Royal Society
of Tropical Medicine and Hygiene, 76: 652-659 (1982)


@chapter[Control Programme]
@Slide[River-PCX-]

@window[This chapter discusses issues regarding schistosomiasis
control programme.  This chapter has not been completed.]


@chapter[Data Analysis]
@Slide[DataAnal-PCX-]
@Window[This chapter will discuss some basic data analysis concepts.
The type data to be collected, the forms used, the analysis
performed, and the format of presentation is discussed.]


@Slide[Data2-Text-]
@Yellow[1.  Introduction]

A schistosomiasis control programme is a far-reaching undertaking whose
preparation and execution, in all its phases, requires the knowledge of
different quantitative information. Existing documentation must be used
rationally by the personnel in each phase of the operations. In addition,
the technical and administrative needs demand the collection and analysis
of appropriate supplementary data.

A single index used to characterize the status of schistosomiasis within a
defined population, such as prevalence [i.e. the proportion of infected
persons], is not adequate to monitor or modify the operations of a control
programme. Other indices are needed especially those relating to the
reduction of morbidity due to schistosomiasis in a treated population. The
statistical analysis should allow the evaluation of the effectiveness of the
campaign during its different phases and make it possible to verify whether
the epidemiological evolution of the disease is as anticipated.

@Slide[Data3-Text-]
@Yellow[2.  THE NEED FOR STATISTICS]

The planning, execution and monitoring of schistosomiasis control programmes
should depend on objective judgements and not on personal expectations. The
data from these programmes are derived from the interactions between three
living groups: human beings, snails [intermediate host] and worms
[schistosomes]. Each of these groups may affect, and may be affected by,
environmental factors known or unknown. The selection of operational
approaches and their modification during the course of the programme
therefore relies on the correct interpretation of interrelated data which
are not only highly variable within themselves but may also be influenced
by a multitude of other uncontrollable factors.

Modern statistical methods facilitate, to a large extent and on a purely
objective basis, the interpretation of numerical data in which variations
may be due to the simultaneous action of many factors. In particular, the
correct interpretation of the data implies the use of appropriate
statistical techniques. For this reason, statistical methods are required
in all phases of a schistosomiasis control programme, in the establishment
of the operational plans as well as in the monitoring of the operations and
the final evaluation of the results.

@Slide[Data4-Text-]
@Yellow[2.1  Analysis of schistosomiasis in a community]

In contrast to the clinician whose major concern is the health of his
patient on an individual basis, the epidemiologist in a control programme
is responsible for the state of health of the community at large. In both
cases, the actions to be taken will depend on the number of persons to be
cared for and the measures of intervention available. However the situation
takes on a statistical nature because the epidemiologist may have to base
his conclusions on the relevant observations from a selected number of
individuals rather than from the whole population. He must establish to what
degree the community is at risk with respect to schistosomiasis, determine
the type, prevalence and intensity of infection, and decide on the
intervention schemes and how best to reduce the risk of the disease within
the community. Although the data will be collected on an individual basis,
the analysis will be focused more on the community as a whole rather than
on the individual. Appropriate statistical methods should then be applied
in the analysis of the collected information.

@Slide[data5-Text-]
@Yellow[2.2  The role of statistics in schistosomiasis control]

Statistics are derived from data recorded for each event or individual. Only
with great difficulty is it possible to grasp all the information that can
be obtained on an individual basis. The capacity of a control programme to
accumulate data usually outstrips its ability to analyze them correctly and
to use them in an informed manner. Statistical methodology is an
indispensable tool for the correct interpretation of the collected data. In
fact it comes directly into play in the various problems faced by a
schistosomiasis control programme of which some of the principal ones are
indicated below.

@Slide[data6-Text-]
2.2.1 Rational planning

      This implies the following:

      -     plans which are flexible and suited to local conditions;

      -     plans which are practicable within the limitations of available
            funds and trained personnel - data processing should be catered
            for;

      -     choosing the geographical area to be covered, the frequency of
            the observations, and the methods and frequency of
            intervention;

      -     establishing reasonable targets for achievement.

@Slide[data7-Text-]
2.2.2 Collection and processing of data

      The correct collection and processing of data include:

      -     the establishment of definitions and the use of standardized
            classifications;

      -     the preparation of questionnaires and appropriate record forms
            with the provision of pre-testing the data collecting
            procedures;

      -     the training of staff in data collection, their supervision and
            the establishment of quality control procedures;

      -     the establishment of appropriate sampling schemes where total
            population coverage is not feasible;

      -     the verification of data with regard to their accuracy,
            correctness and validity.

@Slide[data8-Text-]
2.2.3  Analysis and interpretation of data

      The analysis and interpretation of the collected data consist in:

      -     the sorting and classification of data into the required groups
            for tabular presentation;

      -     the estimation and comparison of the appropriate statistical
            indices and their standard errors;

      -     the evaluation of the campaign results, the statistical
            significance of the conclusions;

      -     the timely preparation of reports on the progress of the
            campaign and their dissemination to those concerned including
            the workers in the field.

It may be necessary to use advanced statistical methods for certain types
of analysis and significance testing, and to have access to computer
facilities for a more efficient processing of the data. Annex 2 gives
examples of tabulations which can be generated during a control programme.

@Slide[Data9-text-]
@Yellow[3.  THE NEED FOR A CENTRAL STATISTICAL SERVICE]

Although the operational approach to be followed during a control programme
should be clearly established, it will continually need to be adapted to the
particular conditions which are met. Various changes may be necessary during
the course of the operations, and sufficient knowledge of the situation is
needed at all times. The data to be used are of a varied nature, coming from
different sources [demographic survey teams, mollusciciding teams,
diagnostic teams, observers, doctors, epidemiologists, administrators
responsible for material and equipment, etc.]. It is therefore indispensable
that all the information collected should be sent to a centralized service
responsible for their collation. The responsibility for the analysis and
interpretation of the data however should not rest solely with the central
statistical service. The capability should be built in at each operational
level of the programme to make specific judgements concerning the
effectiveness and efficiency of the operations within its sector.

@Slide[data10-Text-]

Among the functions of such a centralized service are the following:

      (a)   Keep a permanent control of the statistical documentation
            coming from the different sectors of the operation.
            Centralization may eventually be limited to the data necessary
            for the calculation of relevant fundamental indices:

            -     the prevalence of schistosomiasis, i.e., the results of
                  the parasitological examination;

            -     the actual activities of the control programme [number of
                  potential transmission sites treated with molluscicide,
                  efficiency of the diagnostic teams, etc.].

      (b)   Design surveys appropriate to the local conditions in order to
            estimate indices which cannot be calculated from available
            data.

      (c)   Have a centralized file for the classification of data by
            locality.

@Slide[Data11-Text-]

      (d)   Establish plans for registering the data on standardized forms
            so that they can be stored, retrieved and analyzed, preferably
            by computer.

      (e)   Liaise and collaborate with national health statistical
            services in order to avoid any duplication of effort and to
            correct any eventual differences in the relative numbers of
            known schistosomiasis cases.

      (f)   Verify the accuracy of the information received and study, in
            collaboration with the administrative and technical personnel,
            the possibility of simplifying the registration of the data or
            making it more economical.

      (g)   Establish effective lines of communication so that the data
            from the operational units are not only transmitted to the
            service but are also fed back in an aggregated form to all
            sectors.

@Slide[data12-Text-]
@Yellow[4.  STATISTICS NECESSARY FOR SCHISTOSOMIASIS CONTROL PROGRAMMES]

The need for statistical information becomes apparent during the
preparation of the preliminary investigations that precede the actual
control campaign, and is even more imperative during the phases which
follow. A detailed study of schistosomiasis in each community is based on
knowledge of the demographic, health, economic and social characteristics
of the population itself: i.e., its size, composition by sex and age,
general health status, work conditions, habits, understanding and
awareness of the disease, etc.

@Slide[Data13-Text-]
@Yellow[4.1   Demographic data]

Detailed reports on the status of the population are published
periodically in most countries, usually at the time of the census.
Statistics relating to demographic events such as births, deaths,
marriages, etc., are also published annually by many national governments
in publications on "vital statistics". Furthermore in certain countries
statistics on causes of death are also compiled and published.

While these statistics may not be of great value in the implementation of
control schemes, they will serve as an indicator of the population size.
In general the population census should be established at the outset of
the operations. Each locality should be defined by careful mapping and
the population size determined by a household census. In instances where
a census is not feasible, the best estimate which may be obtained through
discussions with local officials or community leaders may be used. This
estimate should also give some indication of the distribution of the
population by age.

@Slide[Data14-Text-]
@Yellow[4.2   Statistics based on parasitological findings]

The proper monitoring and evaluation of a schistosomiasis control programme
demands that certain indices be calculated both before and during the life
of the programme. The most appropriate indices are based on quantitative
measurements made on the human population.

Indices based on egg counts

  (a)   Prevalence of infection: the proportion of the population infected
        with schistosomiasis, i.e. the proportion of individuals with
        schistosome eggs in their urine or faeces.

  (b)   Prevalence of heavy infections: the proportion of individuals with
        at least 50 eggs/10 ml of urine for S. haematobium infections or with
        at least 100 eggs/gram of faeces for S. mansoni infections.

  (c)   Intensity of infection: this is estimated by the number of eggs per
        unit volume of urine or weight of faeces.

  (d)   Incidence: the rate at which uninfected persons who were never
        treated become infected during a given period of time.

@Slide[Data15-Text-]

All of these measurements are directly affected by the sensitivity of the
diagnostic technique. In the analysis, these indices should be presented
not only for the total population, but also by groups according to age
and sex.

In most control programmes it will be sufficient to calculate only the
first two of the above indices. The last two are more appropriate for
special studies within the programme. For the intensity of infection, it
is recommended that the geometric mean egg output among the infected
individuals be calculated.

@Slide[Data16-Text-]
@Yellow[4.3  Statistics on morbidity due to schistosomiasis]

In most countries the public health services have established a system
for the obligatory declaration of certain infectious diseases, in
particular those considered to be highly contagious and dangerous.
Unfortunately, the majority of schistosomiasis cases are neither treated
in a hospital nor seen by a doctor and therefore are never registered.

However, in some areas, statistics related to the treatment of cases in
hospitals and health centres are often the only sources of information on
the prevalence of schistosomiasis. The interpretation of these data must
be made with great care, because the patients who are treated are not
necessarily representative of the general population, nor even of the
population at risk with respect to schistosomiasis. Hospital statistics
may nevertheless be used to investigate certain aspects of the disease,
as for example the study of seasonal or annual variations in the number
of cases.

@Slide[Data17-Text-]

Since the aims of control programmes are now directed towards a reduction
in morbidity due to schistosomiasis, it is necessary that more up*to-date
and reliable information be obtained in this area both at the beginning
and during the programme.

Indices related to morbidity

  [a]   Within a stated time interval, the number of hospital beds
        occupied by patients with schistosomiasis.

  [b]   The number of outpatient visits related to schistosomal
        infections at dispensaries, health units and hospitals.

        [i]   For S. haematobium infections

            - proportion of persons with recent history of haematuria
              and/or dysuria;
        - prevalence of gross haematuria at time of examination;
            - prevalence of haematuria as detected by chemical reagent
              strips.

@SLide[data18-Text-]

        [ii] For S. mansoni infections

            - proportion of persons with recent history of haematemesis;

            - prevalence of hepatic and/or splenic enlargement in
              schoolchildren [the presence or absence of meso- or
              hyperendemic malaria should be stated].

@Slide[Data19-Text-]
@Yellow[4.4   Statistics on chemotherapy]

Chemotherapy is a tool for both primary and secondary control of
schistosomiasis. The aim of primary control of schistosomiasis is the
reduction in the excretion of eggs, particularly if those persons who are
most likely to pollute the transmission sites, and it is therefore
beneficial for the entire community. The aim of the secondary control of
schistosomiasis is to reduce the risk of morbidity and mortality among
the treated individuals.

Highly effective and well tolerated drugs now exist for the control of
schistosomiasis. The choice of any drug for use in a control programme is
dependent on several factors of which some of the main ones are:

      - the characteristics of transmission of infection,
      - the cost of the drug and the mode of the delivery,
      - the cost of examination of the population,
      - the systems available for providing health care,
      - the estimated degree of acceptance and tolerance of the drug by
        the population.

@Slide[Data20-Text-]

Before carrying out a control programme, therefore, an assessment must be
made of the proposed dosage regime, the mode of delivery and the cost of
identifying and treating the infected individuals.

During the control programme, other indices based on the treatment of the
population may be calculated. Programmes dealing with individuals on a
community basis rather than in a clinical situation require some new
terminology or redefinition of terms. For example, "cure" is a term which
is used in clinical trials and is applied to a patient who does not
excrete eggs on three successive days at some specified time after
treatment [Davis & Bailey, 1969]. For control programmes, it is proposed
that the word "cure" be replaced by the term "egg negative" where "egg
negative"is defined as the absence of Schistosoma eggs in a treated
individual at the subsequent follow-up.

@Slide[data21-Text-]

Indices related to chemotherapy

      [a]   Participation rate: the proportion of infected persons who
            have received treatment. A distinction should be made for
            individuals who are only partially treated in schemes using a
            drug regime requiring more than one dose.

      [b]   Egg negative rate: the proportion of infected persons who
            were treated and who now show an absence of Schistosoma eggs.
            The diagnostic technique used and the time after treatment
            should be stated.

      [c]   Reinfection rate: the proportion of persons who had no
            Schistosoma eggs at the first examination at least three
            months after treatment and who were again found to be
            infected six months or later at a subsequent examination. The
            length of time between examinations should be stated. Usually
            reinfections are observed at about four to six months after
            treatment.

@Slide[Data22-Text-]
@Yellow[5.    OTHER ASSESSMENT INDICES]

Although examination of the human population is essential for the
evaluation of the programme, other indicators may also be taken into
consideration, e.g.:

      * reduction in the snail population;

      - reduced human/water contact;

      - reduced cercarial levels in the water contact sites;

      - introduction/increase of sanitation and water supply.

In order to establish these indicators, information relating to the
environment and to the relationship of human beings to the environment
needs to be ascertained.

@Slide[Data23-Text-]
@Yellow[5.1   Statistics on the snail hosts]

It is neither possible nor necessary to estimate the total number of
snails in a given area. Useful information may be obtained by calculating
certain indices. Studies should first be carried out to determine the
ecological and temporal aspects of the transmission patterns in the areas
concerned. One important index for determining transmission is the water
temperature.

From a practical point of view, it is important to obtain and analyze
data on the proportion of infected snails. Furthermore, it is essential
to relate the snail habits to sites where humans come into contact with
the water and which are contaminated by them.

For snail sampling, the sites and conditions of capture should be chosen
carefully so that the observed differences of snail density reflect the
variations in the environment. Each site within the area where the snails
may be found should be identified by a code number. The list of sites
should be checked regularly and carefully. Periodic surveys should be
made to determine the number of new sites, the sites which may have been
destroyed and the proportion of sites to be treated, etc.

@Slide[Data24-Text-]
@Yellow[5.2   Statistics on mollusciciding]

Snail control by means of molluscicides is a rapid and effective method
of reducing transmission. Its efficiency is increased when it is joined
with other methods of control. Data show that area-wide mollusciciding is
most cost-effective where the volume of water to be treated per individual
at risk is small, as for example in irrigation schemes where population
density is high and where controlled water management is practiced. Focal
mollusciciding, however, is better adapted to zones where there are
seasonal variations in transmission and where the foci are identifiable.
This last method will depend on effective surveillance procedures.

Mollusciciding should be sufficient and regular. "Sufficient"
mollusciciding refers to the amount of molluscicide needed to be
effective in a given volume of water or for a certain length of canal.
Mollusciciding is "regular" if it is repeated at the prescribed
intervals. The control operation will be facilitated if the dates and the
quantity of molluscicide are duly recorded for each site separately so
that the mollusciciding programme may be easily adjusted.

@Slide[data25-Text-]

The efficacy of the mollusciciding programme will also depend on the
ecological situation within the water bodies, the turbidity of the water,
the presence of plants, wave action, water flow, etc. All this
information must be noted with care so that the operations can be planned
to meet the situation.

@Slide[Data26-Text-]
@Yellow[5.3   Statistics on human behaviour with regard to water contact sites]

Since human behaviour plays such an important role in the transmission of
schistosomiasis, any control programme must take into account the human
element. It is essential therefore to determine what knowledge the people
have of the disease and what their attitudes are towards it.

In order to complete the transmission picture, it is necessary to know
the location of the sites where humans come into contact with water, the
human activities in these sites, the presence or the absence of the snail
intermediate host, and the possibilities for human beings to pollute the
water in these sites.

The data may be collected through observations, questionnaires and
interviews. Some of the items on which information may be collected are:

    - location of water contact sites;
    - presence of vegetation and snail hosts;
    - source of water supply and sanitary facilities;
    - identification of the persons having contact with water at the site;
    - type, duration and frequency of contact;
    - perception of water and its relationship with the disease.

@Slide[data27-Text-]

In certain instances it may be possible to relate the prevalence and
intensity of infection in a population with the behaviour and activities
of individual members of the community at defined water contact sites.

If the data are collected during the pre-intervention phase, they can be
utilized in developing the control strategies and in formulating
effective health education programmes.

@Slide[data28-Text-]
@Yellow[6. DATA COLLECTION]

A significant part of all schistosomiasis control programmes involves the
generation of data. These data fall into two main categories: [a] data
dealing with people and [b] data dealing with the environment. The data
concerning people may be further subdivided into those relating to:

      -     demography,
      -     parasitology,
      -     clinical aspects, and
      -     administration of chemotherapy.

      For the environment there are data relating to:

      -     water bodies,
      -     snail hosts,
      -     human activities with respect to the water bodies, and
      -     intervention measures aimed at obtaining some degree of
            transmission control, i.e. mollusciciding, installation of
            water supplies, sanitation and health education.

@Slide[data29-Text-]

The purposes for generating these data will determine the manner in which
they are collected, stored, analyzed and presented. The generation of
data in control schemes is intended to answer certain questions which may
be grouped under three broad headings:

      [1]   To establish baseline data

            Who are the persons at risk?
            Where are the areas of priority?
            How many persons are infected?
            Where are the potential transmission sites?
            What sanitary facilities are available?
            What does the population know about the disease?
            What are their attitudes towards the disease?

@Slide[data30-Text-]

      [2]   To plan the intervention

            Is intervention needed?
            What measures should be undertaken?
            Where, when and how should these measures be applied?
            What are the priorities for applying these measures?

      [3]   To monitor the intervention

            What percentage of the infected people and of the
            transmission sites is being treated?
            How effective are the measures of control?
            Is retreatment necessary?
            When should retreatment take place?
            Which areas or groups of people remain a problem?
            Have sanitary facilities and water supply been provided?
            Are these facilities functioning?
            Are these facilities being used?

@Slide[data31-Text-]

Having stated the purposes for which the data will be used and taking
into due consideration the constraints such as money, personnel and time
so that the resources can be optimally utilized, the control programme
should then proceed to:

      [a]   design record forms and questionnaires to collect the needed
            information;
      [b]   train the personnel in the data collection procedures and in
            correctly and legibly recording the data;
      [c]   establish systems for supervising the collection so as to
            reduce recording errors and keep intra- and inter-observer
            variations down to a minimum.
      [d]   establish systems for processing the data, i.e. checking the
            collected data, coding the information wherever necessary,
            especially when machine processing is envisaged, and editing
            the collected data.
      [e]   establish systems for storing the data.
      [f]   establish systems for analyzing the data.

@Slide[Data32-Text-]
@Yellow[6.1 Sketch maps]

Before the start of the operations a sketch map should be made of every
village or locale in which it is intended to carry out control measures.
This sketch map should include the major features of the locality [roads,
footpaths, water bodies, dwellings, schools, sources of communal water
supply, etc.]. All dwelling units and potential transmission sites should
be numbered and these numbers should be used in the identification
process when recording information related to these places. An example of
a sketch map, which covers two sheets of paper and which was used in the
Philippines, is shown.

@SLide[Data33-Text-]
@Yellow[6.2 Record forms]

Form 01 is an example of a form which may be used for recording data
during the survey and treatment of a population in an area with both
Schistosoma mansoni and S. haematobium infections. The information
gathered by this form would reflect the situation at the time of the
survey and should be used in monitoring and evaluating the effects of the
control programme. The microscopist record forms, Form 02 and Form 03,
would be used in conjunction with the survey record form to inscribe the
results of the parasitological examinations. These forms which offer
suggestions of items to be recorded, should be adapted to meet the
conditions and needs of each control programme. For example, an in-depth
evaluation of the programme would make it necessary to follow people over
time and would therefore require a more detailed identification system
whereby individuals could be easily identified. Form 04 shows the kind of
information which may be collected to of water contact sites. This
information should aid in planning the used at each site. Form 05 is used
to record information concerning one of these control measures.


@chapter[Monitoring & evaluation]
@Slide[Moneval-PCX-]

@window[This chapter will deal with issues on monitoring and
evaulation.  At the end of this chapter, you will know
what is meant by monitoring and evaluation and how
it can be used in schistosomiasis control programme.  This
chapter has not been completed.]



@chapter[Primary health care]
@Slide[Class-PCX-]

@window[This chapter will introduce you to the Primary Health Care
concept.  You will learn about what Primary Health Care means,
what it involves and how it is used for the control of
schistosomiasis.]

@slide[PHC2-Text-Treatment-]
@Yellow[1. INTRODUCTION]

Schistosomiasis is a complex parasitic infection transmitted to man in a
wide variety of freshwater habitats. Four different parasites [S. japonicum,
S. mansoni, S. haematobium and s. intercalatum] are epidemiologically
distinct and affect different organ systems and functional capacity. Disease
or morbidity caused by Schistosoma infection is related to heavy parasite
loads in children acquired by constant contact with freshwater transmission
sites. The chronic disease observed in adults is a sequela of the heavy
infections acquired in childhood.

The recent advances in diagnosis and treatment of schistosomiasis have led
to a reappraisal of control strategy and tactics. The safe, well-tolerated
and highly effective oral antischistosomal drugs, praziquantel, oxamniquine
and metrifonate are now included in the WHO List of Essential Drugs [WHO,
1983a]. In addition, the new rapid, low cost quantitative parasitological
diagnostic techniques are being used efficiently to identify infected
persons.

@Slide[PHC3-Text-]

Programmes to eradicate schistosomiasis by multiple integrated intervention
techniques are beyond the human and financial resources of most endemic
countries and will not achieve their objectives. Reduction of disease due
to schistosomiasis is a feasible objective based on sound epidemiological
principles and can be achieved with the limitations of each endemic country.
As the epidemiology of schistosomiasis varies from one endemic country to
another so the managerial and operational structure of schistosomiasis
control will vary. The simplicity of the diagnostic techniques, the safety
and ease of administration of oral antischistosomal drugs, the use of snail
control measures based on specific epidemiological criteria and precise data
collection and analysis, permit schistosomiasis control activities to be
adapted at any level of the health care delivery system. In primary health
care [PHC] programmes, schistosomiasis control activities to reduce
morbidity can be anticipated to be successful, particularly in
S. haematobium endemic areas.

@Slide[PHCStrat1-Text-]
@Yellow[2.  A STRATEGY FOR THE CONTROL OF MORBIDITY DUE TO SCHISTOSOMIASIS WITHIN]
@Yellow[    A PRIMARY HEALTH CARE APPROACH]

The primary objective of schistosomiasis control is the reduction or
elimination of morbidity due to schistosomiasis. In simpler terms, the
strategy of control is to eliminate or reduce the number of adult
Schistosoma worms in man. The eggs produced by the adult female Schistosoma
are the cause of morbidity due to schistosomiasis. By reduction or
elimination of the adult worms and consequently of the production of eggs
in man, the risk of development of morbidity is reduced.

   The objectives of schistosomiasis control within a PHC approach are:

      (a)   control of morbidity by reduction of prevalence of heavy
            infections by chemotherapy;
      (b)   reduction of overall prevalence of infection;
      (c)   reduction of transmission sites;
      (d)   introduction of sanitation and water supply;
      (e)   as a result of the above, reduction of outpatient visits and
            hospitalizations due to schistosomiasis.

@Slide[PHCMorbid1-Text-]
@Yellow[3.  A PHC APPROACH TO THE CONTROL OF MORBIDITY DUE TO SCHISTOSOMIASIS]

As the epidemiology of schistosomiasis varies from one endemic country to
another so will the managerial and operational structure of schistosomiasis
control activities. The simplicity of the diagnostic techniques, the safety
and ease of administration of oral antischistosomal drugs, the use of snail
control measures based on specific epidemiological criteria and precise data
collection and analysis, permit schistosomiasis control activities to be
adapted at any level of the health care delivery system. In primary health
care programmes, schistosomiasis control activities to reduce morbidity can
be expected to be successful, particularly in S. haematobium endemic areas.

Like any other approach to the control of communicable disease, the primary
health care approach requires adequate training, supervisory organization
and an operational health delivery system. PHC can neither be initiated nor
maintained in isolation from the health care delivery system.

@Slide[PHCMorbid2-Text-]

In relationship to schistosomiasis control and control of other parasitic
diseases, a PHC approach means the utilization of persons from the community
who are trained to explain, interpret and undertake a control programme.
This approach is flexible and adapted to the conditions of each endemic
country or area according to epidemiological, social and cultural
characteristics. To date, there are few successful national experiences with
the PHC approach. Specialized community workers, called "schistosomiasis
agents" are now beginning to be trained in a few areas. Appointed by local
health committees, such persons may be remunerated by the community or
eventually placed on the payroll of the ministry of health. Recognition of
their contribution to schistosomiasis control activities is essential to
maintain a high level of performance and "esprit de corps".

@Slide[PHCMorbid3-Text-]

   The strategies of the PHC approach to schistosomiasis control afford:

      (a)   an entry point for and support to technical and medical
            interventions of specialized mobile teams or personnel;
      (b)   a consistent community level surveillance mechanism to monitor
            the progress of interventions against schistosomiasis;
      (C)   an objective basis to stimulate active involvement of the
            community.

In most endemic areas it may be feasible to implement schistosomiasis
control through PHC programmes. However, unless there is national priority
with proper central technical and medical support and supervision,
integration of schistosomiasis control in PHC programmes should not be
attempted.

@Slide[PHCEpi1-Text-]
@Yellow[4.  THE EPIDEMIOLOGICAL BASIS OF A PHC APPROACH FOR SCHISTOSOMIASIS CONTROL]

The epidemiology of schistosomiasis is not uniform within each endemic
country nor is it comparable between countries. Water resources development
projects for irrigation or other agricultural purposes can modify a
schistosomiasis endemic area with seasonal and highly focal transmission
into an area of intense, widespread, constant transmission. PHC is community
based and thus an appropriate approach to control schistosomiasis whose
epidemiology is so varied.

@Slide[PHCWorker1-Text-]
@Yellow[5.  TASKS OF THE PRIMARY HEALTH CARE WORKER IN SCHISTOSOMIASIS CONTROL]

The tactics of the PHC approach which can be implemented and will directly
affect morbidity due to schistosomiasis are:

     -  data collection for assessment and evaluation;
     -  treatment and follow-up;
     -  health education;
     -  sanitation; and
     -  community participation.

@Slide[PHCWorker2-Text-]
@yellow[5.1   Baseline activities]

Initial assessment of the epidemiological situation of schistosomiasis in
any given endemic area must be made by careful review of available data
and/or by a diagnostic survey with treatment of infected persons conducted
by a specialized mobile team. A PHC worker can assist such a team in
preparing for the specialized activity in a community by carrying out or
participating in the following:

    (a)   prepare a sketch map showing the distribution of houses and
          water contact sites;
    (b)   make a household census of the community which will serve as
          the denominator for all reports;
    (c)   inform community leaders of the forthcoming specialized activity;
    (d)   prepare and motivate community participation.

@Slide[PHCWorker3-Text-]

The PHC worker should have a constructive dialogue with the community
concerning their role in spreading and maintaining schistosomiasis. The role
of women must be emphasized in all aspects of health education. Women's
groups may be convened to discuss personal hygiene, child care, nutrition,
etc., all of which aim to improve the level of understanding of women in
maintaining the health of their children and the community.

@Slide[PHCWorker4-Text-]
@Yellow[5.2  Control activities with specialized teams]

Frequently, the PHC worker will assist and facilitate the initial diagnostic
and treatment surveys of the specialized teams. In direct association with
a specialized mobile team or trained personnel he/she may undertake the
following:

      (a)   parasitological diagnosis;

      (b)   treatment with antischistosomal drugs.

@Slide[PHCWorker5-Text-]
@Yellow[5.3  Supervised activities]

After the initial survey and treatment has been completed, the PHC worker
will continue to monitor the local situation and send periodic reports
through the supervisory channels. With periodic supervision by and reporting
to a central schistosomiasis control programme, the PHC worker will
undertake:

      (a)   epidemiological surveillance;
      (b)   water contact identification and surveillance;
      (c)   human faeces or urine contamination patterns;
      (d)   habitat modification [reduction of transmission sites];
      (e)   community motivation to promote sanitation and establish
            acceptable water supply.


@Slide[PHCDiag1-Text-]
@Yellow[6.  DIAGNOSTIC TECHNIQUES IN SCHISTOSOMIASIS CONTROL]

6.1   Parasitological diagnosis

Current parasitological techniques can be utilized by all levels of
health workers and even minimally trained community members. The costs
related to parasitological diagnosis may be solely initial capital
investments with a low long-term renewal costs.

@lightred[ALL PRICES ARE CITED WITHOUT COMMITMENT IN SECTION 6 AND MUST BE CONFIRMED]
@lightred[BY THE SUPPLIER.]

For further details on the diagnostic procedures a previous document in this
series [WHO/SCHISTO/83.69] may be consulted [WHO, 1983b].

@SLide[PHCDiag2-Text-]
@yellow[6.1.1 The microscope]

The Olympus Model CHC binocular microscope has objectives for stool and
urine examinations as well as the oil immersion objective for examination
of peripheral blood smears for malaria. Its cost is ± US$ 400.

Simplified microscopes developed by R. Rickman at the Tropical Diseases
Research Centre, Ndola, Zambia, under the auspices of the WHO Division of
Diagnostic, Therapeutic and Rehabilitative Technology/Health Laboratory
Technology unit and the WHO Parasitic Diseases Programme/Trypanosomiases and
Leishmaniases unit, are now undergoing evaluation.

@Slide[PHCDiag3-Text-]
@Yellow[6.1.2  The techniques]

@Yellow[6.1.2.1  S. mansoni]

The cellophane faecal thick smear is the technique of choice. A description
of this technique and a list of equipment suppliers is available from the
WHO Parasitic Diseases Programme [see also WHO, 1983c].

(a) Capital costs - reusable/permanent material

      Microscope                    Olympus model CHC       $ 400
      Microscope/slides             1000                       55
      Kato-Katz templates/spatulas  1000                      140
      Stool containers              1000                      100

                                                      Total $ 695
@Slide[PHCDiag4-Text-]

[b]   Operational costs - consumable material

      Cellophane [1 roll]           1500 examinations        0.45
      Plastic screen 160 mesh [m2]  2000 examinations       10.00
      Glycerine/malachite green     10000 examinations       4.00

                                                      Total 14.45

                    Cost/examination US$ 0.0057

Each operational unit should have all of the above material. If no
microscope is available, the slides can be prepared and transported to a
central laboratory facility.

The cost of depreciation, waste and replacement of permanent equipment may
be calculated at 30% per year.

@Slide[PHCDiag5-Text-]
6.1.2.2  S. japonicum

In China, diagnosis of S. japonicum infection at the primary health care
level has been made by the faecal sedimentation hatching technique. This
technique is simple, sensitive and utilizes locally manufactured materials.
If a microscope is not available, a high powered magnifying glass may be
used to detect the miracidia in sunlight.

This technique is not quantitative unless a standard reproducible volume of
stool is examined. The miracidia of S. japonicum can be confused with those
of other trematodes by the inexperienced observer.

@Slide[PHCDiag6-Text-]

Capital costs - reusable/permanent material

      Wire sieve
      Nylon mesh bag [optional
      Clamp for nylon bag [optional]
      Erlenmeyer flask

The technique is fully described in "Handbook on the prevention and
treatment of schistosomiasis" [Shanghai Municipal Institute of Prevention
and Treatment of Schistosomiasis, 1977].

@slide[PHCDiag7-Text-]
@Yellow[6.1.2.3  S. haematobium]

The urine syringe filtration technique using nylon mesh [NytrelR] filters
is appropriate. All material is reusable. Documentation on this technique
and a list of suppliers is available from the WHO Parasitic Diseases
Programme [see also WHO, 1983d].

Capital costs - reusable/permanent material

      Plastic syringes                    1000              $  200
      Plastic extension tubes [6 cm]      1000                  20
      Plastic filter supports             1000              ±  650
      Nylon filters                       10000                200
      Microscope slides                   1000                  55

                                                      Total $ 1025

Each operational PHC unit would have 25 complete filtration sets with 250
nylon filters costing a total of $ 27.00. The major cost is in the filter
support. Lugol's solution may be used to stain the eggs.

@Slide[PHCDiag8-Text-]

The cost of depreciation, waste and replacement of this equipment may be
calculated at 30% per year.

      Other urine filtration techniques utilize:

      (1) polycarbonate membrane filters [NucleporeR]. The filters cannot
      be reused; however it is possible to fix the filter to a microscope
      slide with clear adhesive glue and transport it to a central
      laboratory facility. The cost has recently been reduced to about $
      0.02 each for large volume public sector purchases.

      (2) filter paper with specific stains. The filter paper cannot be
      reused. The quality of the stains must be maintained and the
      staining technique may be difficult under field conditions. The
      cost is low.

@Slide[PHCDiag9-Text-]
@Yellow[6.2  Indirect diagnosis]

If direct quantitative microscopic techniques are not used, then
semiquantitative indirect techniques such as reagent strips to detect
haematuria will aid in identifying heavily infected individuals and in
assessing the impact of the control efforts on morbidity in
S. haematobium areas. Screening of urine specimens from children for
haematuria utilizing reagent strips has been shown to identify 80% of
infected children and nearly all infected children with more than 50 S.
haematobium eggs per 10 ml of urine. The reagent strips are not reusable
and the feasibility for use at primary health care level has not been
evaluated. For large-scale purchases of 500 000 strips, the cost will be
in the region of us$ 0.03-0.05 per strip or lower.

@Slide[PHCDiag10-Text-]

The cost of this approach may be significantly reduced if no previous
antischistosomal treatment has been provided in the endemic area. In such
situations (a) the response to the simple question as to whether the
child (over age 10) has ever passed blood in the urine and (b) the direct
observation of bloody urine, will reduce the requirements for the use of
the chemical reagent strips, especially in endemic areas with a high
prevalence and intensity of infection. Epidemiological information on the
frequency of haematuria in the population, particularly schoolchildren,
as observed at primary health care level would be a valid basis for
determining the priority ranking for schistosomiasis control.

Morbidity due to S. mansoni infection would be difficult to measure in
the primary health care setting. The combined palpation of liver and
spleen size in children to indicate the prevalence of schistosomiasis has
been validated in surveys in West Africa where malaria is endemic.

In adults, information on the frequency of haematemesis or melaena,
though not easy to obtain with reliability, may also be an appropriate
indicator of the need for control measures.

@Slide[PHCRx1-Text-]
@yellow[7.  TREATMENT OF SCHISTOSOMIASIS]

Treatment plays a crucial role in a strategy of morbidity control.
Therefore, although the PHC worker will not be directly responsible for
the administration of antischistosomal drugs, it is important that he
understand the characteristics and effects of the drugs so as to inform
the community better and to be able to cooperate with the specialized
teams.

Effective treatment of schistosomiasis at the community level in order to
control morbidity and have maximal impact on transmission must;

    (a) be given to all infected persons within the shortest period of
        time possible, and
    (b) be administered by medical or specialized trained personnel.

@Slide[PHCRx2-Text-]

Within days after safe, effective antischistosomal drugs are given to all
the infected persons in an endemic community, dramatic effects on the
distribution of schistosomiasis begin to take place. High cure rates are
achieved by all the new antischistosomal drugs. If egg excretion persists
after treatment, the intensity of infection, as measured by the urinary
or faecal egg count, is greatly reduced. After elimination or reduction
of the infection at the time of treatment, the level of contamination by
the original infected population drops significantly. In addition this
"chemotherapeutic shock" reduces the risk of infection of the snail
intermediate hosts. Most importantly, the risk of development of disease
among those who were previously heavily infected is greatly reduced.

All currently listed recommended antischistosomal drugs are on the WHO
Essential Drugs List [WHO, 1983a; see Table 2]. These drugs are not on
the Model List of Drugs for Primary Health Care. The random or occasional
identification of an infected individual does not necessitate immediate
treatment by a PHC worker. Such cases can be referred to nearby medical
facilities.

@Slide[PHCRx3-Text-]

The availability of treatment through PHC workers might unnecessarily
contribute to the risk of resistance appearing on a larger scale. No
resistance to praziquantel has yet been observed nor is the low rate of
resistance to oxamniquine (1%) a hindrance to large-scale treatment
programmes. Antischistosomal drugs may deteriorate rapidly without proper
storage conditions which are usually not available at the community
level. At present, until it is warranted by further experience with
available antischistosomal drugs, unsupervised use by PHC workers is not
recommended. This emphasizes the important role the PHC worker plays in
collaboration with specialized control teams or health centres during
large-scale treatment campaigns to communicate the desirability of
treatment to the community.

WHO and other United Nations agencies are working to obtain the lowest
possible prices for antischistosomal drugs. The specific hard currency
costs of the drugs alone must be balanced against the cost of drug
delivery which in turn depends on the number of doses required for a
complete treatment and the expected duration of the effect of a single
complete treatment.

@Slide[PHCSnail1-text]
@Yellow[8.  SNAIL CONTROL]

The emphasis on the use of specific schistosomiasis chemotherapy must not
be misinterpreted to mean that there is no place for snail control in the
new strategy. On the contrary, now more than ever before, snail control
measures associated with or immediately preceding large-scale use of
chemotherapy may bring about a dramatic reduction in transmission as well
as the expected reduction in prevalence and intensity of infection in the
human population. In some endemic areas, the intensity of transmission is
constant year round and at such a high level that specific chemotherapy
may have little or no effect on the prevalence or intensity of infection.
In other areas, if snail control measures are undertaken, the level of
transmission is reduced so that the effect of the large-scale treatment,
i.e. reduced prevalence and intensity of infection is sustained for a
much longer period of time.

@Slide[PHCSnail2-text-]
@Yellow[8.1  Water contact sites]

The PHC worker may be trained to identify specific locations in and
around the community where schistosomiasis is most likely to be
transmitted. This decision is based on:

      (a)   use of water contact point:   for washing clothes, bathing
            and recreation;
      (b)   use by persons who have clinical manifestations of
            schistosomiasis [i.e. haematuria];
      (c)   use also as a site of defecation and urination;
      (d)   use where intermediate snails are obviously present.

      No equipment is required.

@Slide[PHCSnail3-text-]
@Yellow[8.2  Molluscicides]

Chemical compounds:

     The cost of the only acceptable molluscicide, niclosamide, is high.
     The application of molluscicides by minimally trained PHC personnel at
     village level is being evaluated. No recommendations are available at
     this time.

Plant molluscicides:

     The human toxicity of molluscicides of plant origin has not been
     evaluated. The use of plant molluscicides cannot be recommended at
     this time.

@Slide[PHCSnail4-Text-]
@Yellow[8.3  Habitat modification]

Environmental modification of water contact sites and snail habitats
should be done with community participation. The costs will be absorbed
within improvements for agricultural or water resource management
purposes.

@Slide[PHCHealthEd1-TExt-]
@Yellow[9.  HEALTH EDUCATION]

The PHC worker will be the focal point of the health education process in
the community. His/her role may be twofold depending upon the national
government priority ranking of schistosomiasis control:

      (a)   If a specialized schistosomiasis control programme is
            operational, the PHC worker may be the most important liaison
            between the specialized team and the community.
      (b)   If schistosomiasis control activities are within PHC
            responsibility, the PHC worker may educate the community:

            - on their role in transmission of schistosomiasis;
            - on the impact of schistosomiasis on their daily lives and
              life style; and
            - on their responsibility as community members to eliminate
              the causes of schistosomiasis.

@Slide[PHCHealthEd2-text-]

The failure of sustained control of parasitic diseases in endemic
countries where dramatic short-term results have been obtained should not
be forgotten. All schistosomiasis control programmes in each of their
activities should inform, motivate, train and encourage the community and
their leaders to join in improving their health. If schistosomiasis
control activities are the responsibility of the primary health care
system, the community commitment is essential. There is a danger that
this concept can become jargon and empty rhetoric since it requires
specific action. The PHC worker must be specifically trained to meet the
objectives of health education in his community.

There is a lack of simple practical and durable health education
materials which can be used by PHC workers. Undoubtedly such materials
will be developed and become available in the near future.

@Slide[PHCHealthEd3-text-]

Sanitation, water supply and health education are all important aspects
of schistosomiasis control, but their implementation is usually the
responsibility of governmental agencies other than the Ministry of
Health. The PHC worker may contribute constructively by encouraging
community cooperation in the installation of sanitation and water supply.
The PHC worker's knowledge of customs and habits of the community may be
useful in determining the sites for washing facilities, well drilling and
modification of water bodies for recreation, etc.

@Slide[PHCSurv1-text-]
@Yellow[10.  SURVEILLANCE]

@Yellow[10.1  Epidemiological data]

Careful data recording, collection, processing, analysis and
interpretation is essential. This aspect of control programmes has been
given low priority in the past. Without data based on actual control
activities, the responses to operational questions will remain subjective
and vague. It is critical at the field level that an appropriate data
collection format should be carefully worked out so that data can be
recorded clearly and transferred up through the PHC administrative
hierarchy to those responsible for resource allocation decisions. The
data must also be analyzed and interpreted by PHC supervisors to decide
on necessary operational changes.

@Slide[PHCSurv2-text-]

Within schools, the frequency of the following would be reliable
indicators.

   [a]   In S. haematobium endemic areas:

         - bloody urine specimens among children under 15 years of age
           is an indicator of morbidity;
         - bloody urine specimens among children under 5 years of age
           is a definite indicator of high intensity transmission of
           schistosomiasis.

   [b]   In S. mansoni endemic areas:  indications of morbidity:

         - palpable liver below the xiphoid;
         - enlarged abdomen with collateral circulation and enlarged
           spleen.

@Slide[PHCSurv3-text-]

Within households, the distribution of the following symptoms would
provide useful epidemiological information.

   [a]   In S. haematobium endemic areas [already field tested in Morocco]:

         - visible haematuria [within last month];
         - visible haematuria between 1-6 months ago;
         - pain on urination [dysuria] in the last 6 months;
         - frequency of urination [more than 4 times daily].

   [b]   In S. mansoni endemic areas:

         - frequency of enlarged abdomen with collateral circulation
           and enlarged spleen. In the northeast of Brazil, it is known
           indigenously as "pedra na barriga".

@Slide[PHCSurv4-text-]
@Yellow[10.2  Water contact site identification and surveillance]

Water contact site identification may be carried out by the PHC worker as
indicated in section 8.1.

No equipment is required. A simple form may be completed and is useful in
training PHC workers to understand the epidemiology of schistosomiasis
[WHO, 1983e].

@090370-
11.  TARGETS AND INDICATORS

[1] Reduction of prevalence of morbidity in:

   [a] S. haematobium endemic areas according to:

        Indicators, reported as % of:
        - individuals who have bloody urine at the time of
          examination and within the last month;
        - individuals who have had bloody urine in the past
          [more than 1 month but less than 6 months ago];
        - individuals with dysuria in the last 6 months;
        - young individuals urinating more than 4 times a day;
        - individuals with haematuria by reagent strips at
          the time of examination.

   [b] S. mansoni endemic areas according to:

        Indicators, reported as % of:
        - individuals with a history of haematemesis;
        - school age children with hepatic and splenic enlargement.

@090360-

[2] Reduction of prevalence of heavy infections first in the 5-14 year
    age group then [or simultaneously] in the entire population.

   Indicators

   [a] In S. haematobium endemic areas the number of infections with
       more than 50 eggs per 10 ml of urine should be reduced by 50%
       within one year.

   [b] In S. mansoni endemic areas the number of infections with more
       than 100 eggs per gram of faeces should be reduced by 50% within
       one year.

@090370-

[3] Reduction of prevalence of schistosomiasis in the entire endemic
    population.

    Indicators

    [a] In S. haematobium endemic areas the prevalence should be
        reduced by 30% within one year.

    [b] In S. mansoni endemic areas the prevalence should be reduced by
        20% within one year.

@090380-

[4] To achieve maximum coverage of the community by specialized mobile
    teams as indicated by:

    Indicators, reported as % of:

    - number of parasitological examinations/population census;
    - number of infected individuals treated/number of infected persons.

[5] Reduction of outpatient visits and hospitalizations due to
    schistosomiasis.

[6] Reduction of transmission sites.

@090390-
12.  SUPPORT SYSTEMS

12.1  Epidemiological surveillance reporting

The sequence of flow of information from the PHC worker at the community
level to the appropriate supervisors in the Ministry of Health for
evaluation and response should be fully described. This aspect cannot be
overemphasized.

12.2  Schistosomiasis control interventions

A national schistosomiasis control programme team should support,
coordinate and supervise all schistosomiasis control activities within
PHC. Initiation of schistosomiasis control implies a national plan of
action, a long-term national commitment and priority. Independent or
isolated attempts to control schistosomiasis in single communities by PHC
workers are unwarranted and will be predictably inadequate and
ineffective.

@09040-
12.3  Material and supplies

Equipment and supplies for diagnosis should be available at the community
level when coordinated with the specialized mobile teams. Stool and urine
specimens may be prepared by the PHC workers in anticipation of the
technical personnel who are trained for microscopic examination of the
prepared specimen. This operational approach will facilitate rapid
diagnosis of infected persons and permit treatment of all those infected
within the shortest possible interval.

12.4  Training programmes

The above sections 5 - 10 have reviewed the possible tasks of a PHC
worker. An adequate training programme will be necessary for PHC workers
to acquire the skills needed to implement an effective PHC approach.

Personnel of the national schistosomiasis control programme should
organize training courses for PHC workers. Preparation of a training
manual and educational materials will be required. Periodic training and
evaluation seminArs are advisable.

@09040-
13. LINKAGES WITH OTHER DEVELOPMENT AND HEALTH PROGRAMMES

Schistosomiasis is spreading within agricultural and water resource
development projects throughout the world. At the community level the PHC
worker may be the first health personnel to know of the implementation of
such projects. He may inform the local technical and administrative
personnel of such projects, of the potential spread of schistosomiasis
and of the risk it presents to those exposed within the project area. A
mechanism for reporting new projects to PHC supervisory personnel should
be defined.

The PHC strategy for control of morbidity can be integrated with other
programmes of high priority. In S. mansoni endemic areas, schistosomiasis
control should be closely linked, if not simultaneously, with control of
intestinal helminthiases. Control of S. haematobium [more easily than
S. mansoni] may be easily linked with immunization programmes,
nutritional and other MCH activities, tuberculosis, leprosy and sleeping
sickness surveys, as well as control of diarrhoeal diseases. Programmes
which require systematic repeated surveillance activities may integrate
schistosomiasis control and effectively demonstrate a beneficial effect
of this intervention to the community.

@090420-
TABLE 1. -  SCHISTOSOMIASIS - INFORMATION ON PREVALENCE AND SEVERITY

═══════════════════════════════════════════════════════════════════════════
Type of information        S. haematobium          S. mansoni
───────────────────────────────────────────────────────────────────────────
Prevelence of infection    Eggs present in urine   Eggs present in faeces

Prevalence of            50 eggs/10 ml urine     100 eggs/gram faeces
heavy infection
───────────────────────────────────────────────────────────────────────────
Indicators of recent infection:

   History of haematuria   Within past 6 months
   and/or dysuria

   Haematuria at time of   Gross or detected by
   examination             reagent strip

───────────────────────────────────────────────────────────────────────────
@090430-

───────────────────────────────────────────────────────────────────────────
Indicators of severe infection:                    Haematemesis in adults

                                                   Hepatic and splenic
                                                   enlargement in
                                                   schoolchildren
───────────────────────────────────────────────────────────────────────────
Demand on health services: [health statistics - diagnosed cases]

   Hospital bed occupancy  Symptoms of urinary     Symptoms of S. mansoni
                           schistosomiasis         infection

   Outpatient visits -        Symptoms of urinary     Symptoms of S. mansoni
   at primary health       schistosomiasis         infection
   care dispensary,
   hospital outpatient
   levels


@090440-
          TABLE 2.    RECOMMENDED TREATMENT OF SCHISTOSOMIASIS

════════════════════╤══════════════════════════════╤═══════════════════════
Schistosoma species │ Drug to be used              │ Dosage per kg body wgt
════════════════════╪══════════════════════════════╪═══════════════════════
All species         │ Praziquantel - tablet 600 mg │ 40 mg, single dose
                    │                              │
S. haematobium      │ Metrifonate - tablet 100 mg  │ 7.5 mg, 3 doses
                    │                              │ [1 every 2 weeks]
                    │                              │
S. mansoni          │ Oxamniquine - capsule 250 mg │ 15-60 mg, single dose*
────────────────────┴──────────────────────────────┴───────────────────────
* The customary dose for adults is 15 mg/kg; 20 mg for children and doses
up to 60 mg/kg may be required in Central and East Africa or the Eastern
Mediterranean Region [see WHO, 1983f].


@chapter[Global Database]
@Slide[World-PCX-Mahgreb countries,34,13,49,15-Africa/Central,34,16,49,17-+-
Africa/Southern,40,18,51,20-Asia,53,11,74,17-Americas,20,15,30,22-Mediterranean]

@window[This section contains country profile information of
76 schistosomiasis endemic countries.  The figures are
from WHO/SCHISTO/89.102.Rev.1 - "An Estimate of Global
Needs for Praziquantel Within Schistosomiasis Control
Programmes.  The data is also available on a diskette
from the SCH unit of WHO.]

@Slide[Algeria-PCX-S. haematobium,13,15,26,15-]

Country   : Algeria
WHO Region: AFRO
Population: 21718000
Type      : S. haematobium
At risk   : 5082012
Avg Prev  : 32.00 %

@Slide[Angola-PCX-S. haematobium-S. mansoni-]

Country   : Angola
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 8754000
At risk   : 8754000
Avg Prev  : 44.00 %

@Slide[Antigua-PCX-S. mansoni-]

Country   : Antigua and Barbuda
WHO Region: AMR
Type      : S. mansoni
Population: 80000
At risk   : 400
Avg Prev  : 26.00 %

@Slide[Benin-PCX-S. haematobium-S. mansoni-]

Country   : Benin
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 3932100
At risk   : 3932100
Avg Prev  : 35.50 %

@Slide[Botswana-PCX-S. haematobium-S. mansoni-]

Country   : Botswana
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 1084900
At risk   : 1084900
Avg Prev  : 10.00 %


@Slide[Brazil-PCX-S. mansoni-]

Country   : Brazil
WHO Region: AMR
Type      : S. mansoni
Population: 135564000
At risk   : 30000000
Avg Prev  : 20.00 %

@slide[Burkina-PCX-S. haematobium-S. mansoni-]

Country   : Burkina Faso
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 6639000
At risk   : 6639000
Avg Prev  : 60.00 %

@Slide[Burundi-PCX-S. mansoni-]

Country   : Burundi
WHO Region: AFRO
Type      : S. mansoni
Population: 4717703
At risk   : 2099378
Avg Prev  : 30.00 %

@Slide[Cameroon-PCX-S. haematobium-S. mansoni-S. intercalatum-]

Country   : Cameroon
WHO Region: AFRO
Type      : S. mansoni S. haematobium S. intercalatum
Population: 9873000
At risk   : 8451288
Avg Prev  : 26.50 %

@Slide[CAR-PCX-S. haematobium-S. mansoni-S. intercalatum-]

Country   : Central African Republic
WHO Region: AFRO
Type      : S. mansoni S. haematobium S. intercalatum
Population: 2607800
At risk   : 2607800
Avg Prev  : 10.00 %

@Slide[Chad-PCX-S. haematobium-S. mansoni-S. intercalatum-]

Country   : Chad
WHO Region: AFRO
Type      : S. mansoni S. haematobium S. intercalatum
Population: 5018000
At risk   : 3964220
Avg Prev  : 55.00 %

@Slide[China-PCX-S. japonicum-]

Country   : China
WHO Region: WPRO
Type      : S. japonicum
Population: 1059521000
At risk   : 54106607
Avg Prev  : 1.76 %

@Slide[Congo-PCX-S. haematobium-S. mansoni-S. intercalatum-]

Country   : Congo
WHO Region: AFRO
Type      : S. mansoni S. haematobium S. intercalatum
Population: 1740000
At risk   : 1218000
Avg Prev  : 45.00 %

@Slide[Dominire-PCX-S. mansoni-]

Country   : Dominican Republic
WHO Region: AMR
Type      : S. mansoni
Population: 7012367
At risk   : 4161777
Avg Prev  : 5.00 %

@Slide[Egypt-PCX-S. haematobium-S. mansoni-]

Country   : Egypt
WHO Region: EMRO
Type      : S. mansoni S. haematobium
Population: 52689136
At risk   : 45689136
Avg Prev  : 20.00 %

@Slide[EQUATORI-PCX-S. intercalatum-]

Country   : Equatorial Guinea
WHO Region: AFRO
Type      : S. intercalatum
Population: 392000
At risk   : 78400
Avg Prev  : 10.00 %

@Slide[Ethiopia-PCX-S. haematobium-S. mansoni-]

Country   : Ethiopia
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 43349924
At risk   : 23029900
Avg Prev  : 13.40 %

@Slide[Gabon-PCX-S. haematobium-S. mansoni-S. intercalatum-]

Country   : Gabon
WHO Region: AFRO
Population: 1151000
At risk   : 1151000
Avg Prev  : 45.00 %

@Slide[Gambia-PCX-S. haematobium-S. mansoni-]

Country   : Gambia
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 643000
At risk   : 514400
Avg Prev  : 37.70 %

@Slide[Ghana-PCX-S. haematobium-S. mansoni-]

Country   : Ghana
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 13588000
At risk   : 13588000
Avg Prev  : 72.40 %

@Slide[Guadeloupe-Text-S. mansoni-]

Country   : Guadeloupe
WHO Region: AMR
Type      : S. mansoni
Population: 320000
At risk   : 169600
Avg Prev  : 15.00 %

@slide[Guinea-PCX-S. haematobium-S. mansoni-]

Country   : Guinea
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 6075000
At risk   : 6075000
Avg Prev  : 25.00 %

@Slide[GuineaB-PCX-S. haematobium-S. mansoni-]

Country   : Guinea-Bissau
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 890000
At risk   : 890000
Avg Prev  : 30.00 %

@Slide[India-PCX-S. haematobium-]


Country   : India
WHO Region: SEARO
Type      : S. haematobium
Population: 750900000
At risk   :  912
Avg Prev  : 2.00 %

@Slide[IndonesiA-PCX-S. japonicum-]

Country   : Indonesia
WHO Region: SEARO
Type      : S. japonicum
Population: 163393250
At risk   : 8000
Avg Prev  : 2.20%

@Slide[Iran-Text-S. haematobium-]

Country   : Iran
WHO Region: EMRO
Type      : S. haematobium
Population: 44632000
At risk   : 2901080
Avg Prev  : 1.00 %

@Slide[Iraq-Text-S. haematobium-]

Country   : Iraq
WHO Region: EMRO
Type      : S. haematobium
Population: 15898000
At risk   : 4184742
Avg Prev  : 0.46 %

@Slide[IvoryC-Text-S. haematobium-S. mansoni-]

Country   : Ivory Coast
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 9810000
At risk   : 9810000
Avg Prev  : 40.00 %

@Slide[Japan-Text-S. japonicum-]

Country   : Japan
WHO Region: WPRO
Type      : S. japonicum
Population: 120754335
At risk   :    0
Avg Prev  : 0.00 %

@Slide[Jordon-Text-S. haematobium-]

Country   : Jordan
WHO Region: EMRO
Type      : S. haematobium
Population: 3515000
At risk   : 20000
Avg Prev  : 0.10 %

@Slide[DKampuchea-Text-S. japonicum-]

Country   : Democratic Kampuchea
WHO Region: WPRO
Type      : S. mekongi
Population: 7284000
At risk   : 500000
Avg Prev  : 10.00 %

@Slide[Kenya-Text-S. haematobium-S. mansoni-]

Country   : Kenya
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 20333275
At risk   : 20333275
Avg Prev  : 23.00 %

@Slide[Laos-Text-S. japonicum-]

Country   : Lao People's Democratic Republic
WHO Region: WPRO
Type      : S. mekongi
Population: 4117000
At risk   : 400000
Avg Prev  : 25.00 %

@Slide[Lebanon-Text-S. haematobium-]

Country   : Lebanon
WHO Region: EMRO
Type      : S. haematobium
Population: 2668000
At risk   :  0
Avg Prev  : 0.00 %

@slide[Liberia-Text-S. haematobium-S. mansoni-]

Country   : Liberia
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 2189033
At risk   : 1751226
Avg Prev  : 30.00 %

@Slide[Libya-Text-S. haematobium-S. mansoni-]

Country   : Libyan Arab Jamahiriya
WHO Region: EMRO
Type      : S. mansoni S. haematobium
Population: 3605000
At risk   : 1202000
Avg Prev  : 15.00 %

@Slide[madagascar-Text-S. haematobium-S. mansoni-]

Country   : Madagascar
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 9985000
At risk   : 9985000
Avg Prev  : 55.00 %

@Slide[Malawi-Text-S. haematobium-S. mansoni-]

Country   : Malawi
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 7058800
At risk   : 7058800
Avg Prev  : 42.50 %

@Slide[Malaysia-Text-S. japonicum-]

Country   : Malaysia
WHO Region: SEARO
Type      : S. japonicum [resembles]
Population: 17000000
At risk   :   0
Avg Prev  : 0.00 %

@slide[mali-Text-S. haematobium-S. mansoni-]

Country   : Mali
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 8205582
At risk   : 8205582
Avg Prev  : 60.00 %

@slide[Martinique-Text-S. mansoni-]

Country   : Martinique
WHO Region: AMR
Type      : S. mansoni
Population: 315000
At risk   : 55125
Avg Prev  : 7.60 %

@Slide[Mauritania-TEXT-S. haematobium-]

Country   : Mauritania
WHO Region: AFRO
Type      : S. haematobium
Population: 1888000
At risk   : 1888000
Avg Prev  : 27.60 %

@Slide[Mauritius-Text-S. haematobium-]

Country   : Mauritius
WHO Region: AFRO
Type      : S. haematobium
Population: 1016596
At risk   : 341508
Avg Prev  : 4.20 %

@Slide[Montserrat-Text-S. mansoni-]

Country   : Montserrat
WHO Region: AMR
Type      : S. mansoni
Population: 11200
At risk   : 145
Avg Prev  : 17.50 %

@Slide[Morocco-PCX-S. haematobium-]

Country   : Morocco
WHO Region: EURO
Type      : S. haematobium
Population: 21941000
At risk   : 650000
Avg Prev  : 8.00 %

@SLide[Mozambique-Text-S. haematobium-S. mansoni-]

Country   : Mozambique
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 13961000
At risk   : 13961000
Avg Prev  : 69.70 %

@Slide[Namibia-Text-S. haematobium-S. mansoni-]

Country   : Namibia
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 800000
At risk   : 100000
Avg Prev  : 5.00 %

@Slide[Niger-Text-S. haematobium-S. mansoni-]

Country   : Niger
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 6115000
At risk   : 6115000
Avg Prev  : 26.70 %

@Slide[Nigeria-Text-S. haematobium-S. mansoni-]

Country   : Nigeria
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 95198000
At risk   : 86387000
Avg Prev  : 25.50 %

@Slide[Oman-Text-S. mansoni-]

Country   : Oman
WHO Region: EMRO
Type      : S. mansoni
Population: 1242000
At risk   : 1000
Avg Prev  : 7.40 %

@Slide[Philippines-Text-S. japonicum-]

Country   : Philippines
WHO Region: WPRO
Type      : S. japonicum
Population: 54377993
At risk   : 5000000
Avg Prev  : 6.90 %

@Slide[PuertoRico-Text-S. mansoni-]

Country   : Puerto Rico
WHO Region: AMR
Type      : S. mansoni
Population: 3410000
At risk   : 682000
Avg Prev  : 2.00 %

@Slide[Rwanda-Text-S. mansoni-]

Country   : Rwanda
WHO Region: AFRO
Type      : S. mansoni
Population: 6070000
At risk   : 3642000
Avg Prev  : 10.00 %

@Slide[SaintLucia-Text-S. mansoni-]

Country   : Saint Lucia
WHO Region: AMR
Type      : S. mansoni
Population: 130000
At risk   : 15860
Avg Prev  : 0.60 %

@Slide[SaoTome-Text-S. haematobium-]

Country   : Democratic Republic of Sao Tome and Principe
WHO Region: AFRO
Type      : S. haematobium
Population: 108163
At risk   : 20000
Avg Prev  : 20.00 %

@Slide[SaudiArabia-Text-S. haematobium-S. mansoni-]

Country   : Saudi Arabia
WHO Region: EMRO
Type      : S. mansoni S. haematobium
Population: 11542000
At risk   : 1965683
Avg Prev  : 5.10 %

@Slide[Senegal-Text-S. haematobium-S. mansoni-]

Country   : Senegal
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 6444000
At risk   : 6444000
Avg Prev  : 15.00 %

@Slide[SierraL-Text-S. haematobium-S. mansoni-]

Country   : Sierra Leone
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 3602000
At risk   : 3169760
Avg Prev  : 67.70 %

@Slide[Somalia-Text-S. haematobium-]

Country   : Somalia
WHO Region: EMRO
Type      : S. haematobium
Population: 4653000
At risk   : 2326500
Avg Prev  : 36.00 %

@Slide[SAfrica-Text-S. haematobium-S. mansoni-]

Country   : South Africa
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 32392000
At risk   : 20000000
Avg Prev  : 17.50 %

@Slide[Sudan-Text-S. haematobium-S. mansoni-]

Country   : Sudan
WHO Region: EMRO
Type      : S. mansoni S. haematobium
Population: 21550000
At risk   : 19395000
Avg Prev  : 20.20 %

@Slide[Suriname-Text-S. mansoni-]

Country   : Suriname
WHO Region: AMR
Type      : S. mansoni
Population: 375000
At risk   : 34000
Avg Prev  : 10.00 %

@Slide[Swazil-Text-S. haematobium-S. mansoni-]

Country   : Swaziland
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 647415
At risk   : 647415
Avg Prev  : 25.00 %

@Slide[Syria-Text-S. haematobium-]

Country   : Syrian Arab Republic
WHO Region: EMRO
Type      : S. haematobium
Population: 10267000
At risk   : 983000
Avg Prev  : 0.20 %

@Slide[Tanzania-Text-S. haematobium-S. mansoni-]

Country   : United Republic of Tanzania
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 21730000
At risk   : 21730000
Avg Prev  : 51.50 %

@Slide[Thailand-Text-S. japonicum-]

Country   : Thailand
WHO Region: SEARO
Type      : S. japonicum [resembles]
Population: 51301000
At risk   :   0
Avg Prev  : 0.00 %

@Slide[Togo-Text-S. haematobium-S. mansoni-]

Country   : Togo
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 2960000
At risk   : 2960000
Avg Prev  : 25.00 %

@SLide[Tunisia-Text-S. haematobium-]

Country   : Tunisia
WHO Region: EMRO
Type      : S. haematobium
Population: 7816000
At risk   : 350000
Avg Prev  : 0.05 %

@Slide[Turkey-Text-S. haematobium-]

Country   : Turkey
WHO Region: EURO
Type      : S. haematobium
Population: 49272000
At risk   : 50000
Avg Prev  : 1.00 %

@Slide[Uganda-Text-S. haematobium-S. mansoni-]

Country   : Uganda
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 15477000
At risk   : 15477000
Avg Prev  : 32.00 %

@Slide[Venezuela-Text-S. mansoni-]

Country   : Venezuela
WHO Region: AMR
Type      : S. mansoni
Population: 17316738
At risk   : 4502352
Avg Prev  : 0.60 %

@Slide[Yemen-Text-S. haematobium-S. mansoni-]

Country   : Yemen Arab Republic
WHO Region: EMRO
Type      : S. mansoni S. haematobium
Population: 6849000
At risk   : 6849000
Avg Prev  : 14.60 %

Country   : Yemen, Democratic
WHO Region: EMRO
Type      : S. mansoni S. haematobium
Population: 2293910
At risk   : 1000000
Avg Prev  : 13.10 %

@Slide[Zaire-Text-S. haematobium-S. mansoni-S. intercalatum-]

Country   : Zaire
WHO Region: AFRO
Type      : S. mansoni S. haematobium S. intercalatum
Population: 30362751
At risk   : 23691690
Avg Prev  : 36.20 %

@Slide[Zambia-Text-S. haematobium-S. mansoni-]

Country   : Zambia
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 6666000
At risk   : 6666000
Avg Prev  : 26.50 %

@Slide[Zimbabwe-Text-S. haematobium-S. mansoni-]

Country   : Zimbabwe
WHO Region: AFRO
Type      : S. mansoni S. haematobium
Population: 8300000
At risk   : 8300000
Avg Prev  : 40.00 %

@END