Following is an extract of the the final electronic text from the Morbidity and Mortality Weekly Report (MMWR) Recommendations and Reports, vol. 39, No. RR-13, dated October 19, 1990. The MMWR is published by the U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention (CDC), Epidemiology Program Office, Atlanta, Georgia 30333. a
INTRODUCTION
CREDITS
DEFINITIONS
DEFINITIONS
REFERENCES
SUGGESTED CITATION
Centers for Disease Control. Case definitions for public health surveillance. MMWR 1990;39(No. RR-13):(inclusive page numbers).
CREDITS
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definitions
Centers for Disease Control
William L. Roper, M.D., Dr.P.H., Director
Epidemiology Program Office
Stephen B. Thacker, M.D., M.Sc., Director
Richard A. Goodman, M.D., M.P.H., Editor, MMWR Series
--
Division of Surveillance and Epidemiologic Studies
Steven M. Teutsch, M.D., M.P.H., Director
--
Epidemiology and Surveillance Branch
Joseph Mulinare, M.D., M.S.P.H., Chief
--
Editorial Services
R. Elliott Churchill, M.A., Chief
Suzanne M. Hewitt, Norma W. Strawn, Writer-Editors
Julie T. Creasy, Ruth C. Greenberg, Editorial Assistants
Case Definitions for Public Health Surveillance
Melinda Wharton, M.D., M.P.H., Centers for Disease Control (CDC) Terence L. Chorba, M.D., M.P.H., CDC Richard L. Vogt, M.D., Council of State and Territorial
Epidemiologists (CSTE)
Dale L. Morse, M.D., M.S., CSTE James W. Buehler, M.D., CDC
The authors were assisted by Joel R. Greenspan, M.D., M.P.H., Stephen L. Cochi, M.D., Steven L. Solomon, M.D., Joseph E. Sniezek, M.D., M.P.H., Alan B. Bloch, M.D., M.P.H., Steven M. Teutsch, M.D., M.P.H., and the Council of State and Territorial Epidemiologists. 2
Use of trade names is for identification only and does not imply endorsement by the Public Health Service or the U.S. Department of Health and Human Services.Copies can be purchased from Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402-9325. Telephone: (202) 783-3238.
definitions
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Gonorrhea
Haemophilus
influenzae
(Invasive
Disease)
Hepatitis,
Viral
Measles
Meningococcal
Disease
Salmonellosis
INTRODUCTION
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definitions
Public health officials rely on health providers, laboratories, and other public health personnel to report the occurrence of notifiable diseases to state and local health departments. Without such data, monitoring trends or evaluating the effectiveness of intervention activities would be difficult. B
The Council of State and Territorial Epidemiologists (CSTE) has recommended that state health departments report cases of selected diseases (Table 1) to CDC's National Notifiable Diseases Surveillance System (NNDSS). However, the usefulness of such data has been limited by the lack of uniform case definitions for public health surveillance (1). Without explicit criteria for identifying cases, state health departments and individual practitioners have used various criteria for case reporting. This document, prepared in cooperation with the CSTE, provides uniform criteria for reporting purposes. States that wish to improve the specificity of reporting may find the definitions helpful. As uniform case definitions are adopted, the incidence of reported diseases in different geographic areas may be more meaningfully compared.
In the United States, requirements for reporting diseases are mandated by state laws or regulations, and the list of reportable diseases in each state varies. A summary of state requirements for notifiable diseases has recently been published (2). National data from the NNDSS are collated and published weekly in the Morbidity and Mortality Weekly Report (MMWR). In general, cases reported by state health departments to the NNDSS are provisional. Updated final reports are published annually in the Summary of Notifiable Diseases. U
Additionally, state health departments provide CDC information about these and other conditions of public health interest through supplementary surveillance systems that collect more detailed, condition-specific information (3). These conditions may or may not be included in the state laws or regulations that mandate reporting (Table 2).
The CSTE/CDC surveillance case definitions included in this document vary in their use of clinical, laboratory, and epidemiologic criteria to define cases. Some clinical syndromes do not have confirmatory laboratory tests, but laboratory evidence may be one component of a clinical definition; toxic shock syndrome is an example. Other diseases (e.g., mumps) have such a characteristic clinical presentation that, even in the absence of confirmatory laboratory testing, a diagnosis may be based only on clinical findings. In most instances, a brief clinical description is provided. Unless the clinical description is explicitly cited in the
Case classification
section of each definition, it is included only as background information.
Some diseases require laboratory confirmation for diagnosis, regardless of clinical symptomatology, and some are diagnosed on the basis of epidemiologic data. Many of the childhood vaccine-preventable diseases include epidemiologic criteria (e.g., exposure to probable or confirmed cases of disease) in the case definitions. In some instances, the site of infection may be important; pharyngeal diphtheria is notifiable, for example, whereas cutaneous diphtheria is not. a
For many diseases, substantial amounts of information, including results of laboratory tests, must be collected before a final case classification is possible. State health departments are requested to continue reporting provisional cases to the NNDSS promptly, and records should be updated when additional surveillance information becomes available. w
Surveillance demands uniformity, simplicity, and brevity. These case definitions are intended to establish uniform criteria for disease reporting; they should not be used as sole criteria for establishing clinical diagnoses, determining the standard of care necessary for a particular patient, setting guidelines for quality assurance, providing standards for reimbursement, or initiating public health actions. Use of additional clinical, epidemiologic, and laboratory data may enable a physician to diagnose a disease even though the surveillance case definition may not be met. For example, an adolescent with bilateral orchitis who attends a school in which a mumps outbreak is occurring would not meet the surveillance case definition for mumps unless the mumps virus was isolated. However, clinical judgment would suggest that in this situation, viral isolation is not necessary. +
As knowledge increases and diagnostic technology improves, some definitions will change to reflect those trends. For example, many cases of non-A, non-B hepatitis are due to the recently described hepatitis C virus (4). Therefore, revisions, additions, and deletions can be expected in the future.
DEFINITION
TERMS
CLASSIFICATION
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definitions
Confirmed case:
a case that is classified as confirmed for reporting purposes. O
Probable case:
a case that is classified as probable for reporting purposes. @
Laboratory-confirmed case:
a case that is confirmed by one or more of the laboratory methods listed in the case definition under "Laboratory criteria for diagnosis." Although other laboratory methods may be used in clinical diagnosis, only those listed are accepted for laboratory confirmation for reporting purposes.
Clinically compatible case:
a clinical syndrome generally compatible with the disease, but no specific clinical criteria need to be met unless they are noted in the case classification.
Supportive laboratory results:
specified laboratory results consistent with the diagnosis but not meeting the criteria for laboratory confirmation. o
Epidemiologically linked case:
a case in which the patient has/has had contact with one or more persons who have/had the disease, and transmission of the agent by the usual modes of transmission is plausible. A case may be considered epidemiologically linked to a laboratory-confirmed case if at least one case in the chain of transmission is laboratory confirmed.
Meets the clinical case definition:
meets precisely the clinical case definition. Although in clinical practice the diagnosis may be made with the use of other criteria, for reporting purposes the stated criteria must be met.
Gonorrhea
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definitions
Clinical description
A sexually transmitted infection commonly manifested by urethritis, cervicitis, or salpingitis. Infection may be asymptomatic. %
Laboratory criteria for diagnosis
Isolation of Neisseria gonorrhoeae from a clinical specimen, or a
Observation of gram-negative intracellular diplococci in a urethral smear obtained from a man
Case classification
Probable:
demonstration of gram-negative intracellular diplococci in an endocervical smear obtained from a woman, or a written (morbidity) report of gonorrhea submitted by a physician 1
Confirmed:
a case that is laboratory confirmed
Haemophilus
influenzae
(Invasive
Disease)
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definitions
Clinical description
Invasive disease due to Haemophilus influenzae may produce any of several clinical syndromes, including meningitis, bacteremia, epiglottitis, or pneumonia %
Laboratory criteria for diagnosis
Isolation of H. influenzae from a normally sterile site
Case classification
Probable:
a clinically compatible illness with detection of H. influenzae type b antigen in cerebrospinal fluid G
Confirmed:
a clinically compatible illness that is culture confirmed
Comment
Antigen test results in urine or serum are unreliable for diagnosis of H. influenzae disease.
Hepatitis,
Viral
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Clinical case definition
An illness with a) discrete onset of symptoms and b) jaundice or elevated serum aminotransferase levels %
Laboratory criteria for diagnosis
Hepatitis A: IgM anti-HAV-positive g
Hepatitis B: IgM anti-HBc-positive (if done) or HBsAg-positive, and IgM anti-HAV-negative (if done)
Non-A, Non-B Hepatitis:
1.IgM anti-HAV-negative, and :
2.IgM anti-Hbc-negative (if done) or Hbsag-negative, and T
3.Serum aminotransferase levels greater than 2 1/2 times the upper limit of normal J
Delta Hepatitis: Hbsag- or IgM anti-Hbc-positive and anti-HDV-positive
Case classification
Confirmed:
a case that meets the clinical case definition and is laboratory confirmed
Comment
A serologic test for IgG antibody to the recently described hepatitis C virus is available, and many cases of non-A, non-B hepatitis may be demonstrated to be due to infection with the hepatitis C virus. With this assay, however, a prolonged interval between onset of disease and detection of antibody may occur. Until a more specific test for acute hepatitis C becomes available, these cases should be reported as non-A, non-B hepatitis. Chronic carriage or chronic hepatitis should not be reported.
Measles
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definitions
Clinical case definition
An illness characterized by all of the following clinical features: >
a generalized rash lasting greater than or equal to 3 days 9
a temperature greater than or equal to 38.3 C (101 F) '
cough, or coryza, or conjunctivitis %
Laboratory criteria for diagnosis
Isolation of measles virus from a clinical specimen, or R
Significant rise in measles antibody level by any standard serologic assay, or 4
Positive serologic test for measles IgM antibody
Case classification
Suspect: any rash illness with fever
Probable:
meets the clinical case definition, has no or noncontributory serologic or virologic testing, and is not epidemiologically linked to a probable or confirmed case
Confirmed:
a case that is laboratory confirmed or that meets the clinical case definition and is epidemiologically linked to a confirmed or probable case. A laboratory-confirmed case does not need to meet the clinical case definition.
Comment
Two probable cases that are epidemiologically linked would be considered confirmed, even in the absence of laboratory confirmation. Only confirmed cases should be reported to the NNDSS.
Meningococcal
Disease
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definitions
Clinical description
Meningococcal disease presents most commonly as meningitis and/or meningococcemia that may progress rapidly to purpura fulminans, shock, and death. However, other manifestations may be observed. %
Laboratory criteria for diagnosis
Isolation of Neisseria meningitidis from a normally sterile site
Case classification
Probable:
a positive antigen test in cerebrospinal fluid or clinical purpura fulminans in the absence of a positive blood culture D
Confirmed:
a clinically compatible case that is culture confirmed
Comment
Antigen test results in urine or serum are unreliable for diagnosing meningococcal disease.
Salmonellosis
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Clinical description
An illness of variable severity commonly manifested by diarrhea, abdominal pain, nausea, and sometimes vomiting. Asymptomatic infections may occur, and the organism may cause extraintestinal infections. %
Laboratory criteria for diagnosis
Isolation of Salmonella from a clinical specimen
Case classification
Probable:
a clinically compatible illness that is epidemiologically linked to a confirmed case 1
Confirmed:
a case that is laboratory confirmed
Comment
Both probable and confirmed cases are reported to the NNDSS, but only confirmed cases are reported to the laboratory-based surveillance system operated by the Enteric Diseases Branch, Center for Infectious Diseases, CDC. Both asymptomatic infections and infections at sites other than the gastrointestinal tract, if laboratory confirmed, are considered confirmed cases.
References
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1. Sacks JJ. Utilization of case definitions and laboratory reporting in the surveillance of notifiable communicable diseases in the United States. Am J Public Health 1985;75:1420-2.
2. Chorba TL, Berkelman RL, Safford SK, et al. Mandatory reporting of infectious diseases by clinicians. JAMA 1989;262:3018-26.
3. CDC. Manual of procedures for national morbidity reporting and public health surveillance activities. Atlanta: US Department of Health and Human Services, Public Health Service, 1985.
4. Kuo G, Choo Q-L, Alter HJ, et al. An assay for circulating antibodies to a major etiologic virus of human non-A, non-B hepatitis. Science 1989;244:362-4.
5. Broome CV, Fraser DW, English WJ. Pertussis--diagnostic methods and surveillance. In: Manclark CR, Hill JC, eds. International Symposium on Pertussis. Bethesda, Maryland: National Institutes of Health, 1978;19-22.
6. Halperin SA, Bartolussi R, Wort AJ. Evaluation of culture, immunofluorescence and serology for the diagnosis of pertussis. J Clin Microbiol 1989;27:752-7.
7. American Heart Association. Jones criteria (revised) for guidance in the diagnosis of rheumatic fever. Circulation 1984;69:204A-8A.
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