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Copyright (C) 1986 National Organization for Rare Disorders, Inc.

171:
Cysticercosis

General Discussion

** REMINDER **
The information contained in the Rare Disease Database is provided for
educational purposes only.  It should not be used for diagnostic or treatment
purposes.  If you wish to obtain more information about this disorder, please
contact your personal physician and/or the agencies listed in the "Resources"
section of this report.


Cysticercosis is a complication of severe tapeworm infections acquired by
eating uncooked pork.  The disorder is caused by larval pork tapeworms.  The
scientific name for this parasite is Taenia solium.  Cysticerci are immature
tapeworms which normally live in the muscle (meat) of swine.  When they
develop instead in human muscle and die, they can cause severe inflammatory
reactions.  Cysticercosis is a rare disorder in the United States, Western
Europe, Japan and in non-pork eating cultures.

Symptoms

In Cysticercosis, heavy infection with larval pork tapeworms, or cysticerci,
is characterized by muscle pains, fever, and weakness.  Although the
cysticerci usually restrict themselves to muscle and subcutaneous tissues,
they may occasionally invade the central nervous system where they can cause
epilepsy or inflammation of the brain and its covering membranes.  Other
organs occasionally involved are the eye, heart and lung.  Ocular
manifestations include inflammation of the various structures of the eye and
detachment or hemorrhaging of the retina.

As long as these larvae remain alive, they appear to be able to
"disguise" themselves from the host's immune system causing only mild
symptoms.  When one of them dies, however, there is a strong immune defensive
reaction against it or the cyst surrounding it.  The cyst itself may become
enormous.  Such inflammatory reactions can cause severe illness, particularly
if the cysticercus is lodged in the central nervous system or lung.

Causes

Cysticercosis results from eating inadequately cooked pork containing
tapeworm eggs.  The normal life cycle of pork tapeworms is as follows:  the
pig ingests tapeworm eggs (released through the stool from adult tapeworms
living in the intestine of a human host).  In the pig's intestine, the eggs
hatch and burrow through the gut wall into muscle tissue.  There they encyst
and develop into larvae called cysticerci.  When the pig is killed and its
meat eaten by a person, the cysticerci are released and attach themselves to
the wall of the intestine where they develop into egg producing adult
tapeworms.

When an individual ingests tapeworm eggs (rather than the larvae), these
also find their way into the muscle, subcutaneous tissue, etc.  But because
humans are not normally eaten, the eggs remain in these tissues indefinitely,
unable to proceed to the next stage of their life cycle.  Thus, they may
eventually die causing the severe inflammatory reactions described above.

Cysticercosis can also develop if regular tapeworm infections are treated
carelessly.  Killing the adult tapeworms pharmaceutically causes them to
release large numbers of eggs into the intestine and some of these may enter
the intestinal wall as described above.

Affected Population

Pork tapeworm infections, and therefore Cysticercosis, are common only in
Asia, Russia, Eastern Europe, and Latin America.

Related Disorders

Tapeworms can be acquired from various uncooked meats, including beef and
fish, but only pork tapeworms appear to produce larvae capable of invading
human muscle and forming cysts.

Therapies:  Standard

Thoroughly cooking pork before eating it prevents infection with pork
tapeworm.  Special care must be taken when cooking pork in microwave ovens to
assure the meat is well cooked.  Established tapeworms can be eliminated
using antiparasitic medications such as niclosamide or paronomycin.  As
described above, care must be taken to avoid the release of large quantities
of eggs from the dying tapeworms as this may cause Cysticercosis.  Large
cysts containing cysticerci are usually removed surgically.

Therapies:  Investigational

This disease entry is based upon medical information available through
September 1989.  Since NORD's resources are limited, it is not possible to
keep every entry in the Rare Disease Database completely current and
accurate.  Please check with the agencies listed in the Resources section for
the most current information about this disorder.

Resources

For more information on Cysticercosis, please contact:

     National Organization for Rare Disorders (NORD)
     P.O. Box 8923
     New Fairfield, CT  06812-1783
     (203) 746-6518

     Centers for Disease Control (CDC)
     1600 Clifton Road, NE
     Atlanta, GA  30333
     (404) 639-3534

     NIH/National Institute of Allergy and Infectious Diseases
     9000 Rockville Pike
     Bethesda, MD  20892
     (301) 496-5717

References

CECIL TEXTBOOK OF MEDICINE, 18th ed.:  James B. Wyngaarden, and Lloyd H.
Smith, Jr., Eds.:  W. B. Saunders Co., 1988.  P. 1892.

THE MERCK MANUAL 15th ed:  R. Berkow, et al:  eds; Merck, Sharp & Dohme
Research Laboratories, 1987.  P. 229.