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close this bookWHO Recommended Surveillance Standards (WHO; 1999; 157 pages)
View the documentAcknowledgements
View the documentAcronyms
View the documentIntroduction
View the documentNational Coordination of Communicable Disease Surveillance
View the documentExplanatory notes
View the documentSurveillance activities: criteria and WHO Department
View the documentCommunicable disease contacts in Regional Offices
close this folderDiseases
View the documentB20-B21-B22-B23-B24 AIDS
View the documentA22 Anthrax
View the documentA23 Brucellosis
View the documentA00 Cholera
View the documentA81.0 Creutzfeldt-Jakob disease
View the documentA90, A91 Dengue fever (A90) including Dengue haemorrhagic fever (DHF) & Dengue shock syndrome (DSS, A91)
View the documentA36 Diphtheria
View the documentB72 Dracunculiasis (Guinea worm disease)
View the documentA98.3, A98.4 Ebola-Marburg viral diseases
View the documentA83.0 Japanese encephalitis
View the documentB74 Lymphatic filariasis
View the documentB96.3 Haemophilus influenzae type b
View the documentB15-B17 Acute viral hepatitis
View the documentB20-B24 HIV infection
View the documentJ10, J11 Influenza
View the documentA96.2 Lassa fever
View the documentA48.1 Legionellosis
View the documentB55.1, B55.2 Cutaneous leishmaniasis
View the documentLeishmania / HIV co-infections
View the documentB55.0 Visceral leishmaniasis
View the documentA30 Leprosy
View the documentA27 Leptospirosis
View the documentB50-54 Malaria
View the documentB05 Measles
View the documentA39 Meningococcal disease
View the documentA87 Viral meningitis
View the documentB73 Onchocerciasis
View the documentA37.0 Pertussis
View the documentA20 Plague
View the documentA36 Poliomyelitis
View the documentA82 Rabies
View the documentA02.0 Salmonellosis
View the documentB65 Schistosomiasis
View the documentA50-52 Syphilis
View the documentA33 Tetanus, neonatal
View the documentB56-0, B56-1 African trypanosomiasis
View the documentB57 American trypanosomiasis
View the documentA15-A19 Tuberculosis
View the documentA75.3 Scrub typhus
View the documentA95.9 Yellow fever
open this folder and view contentsSyndromes
View the documentAnnex 1 Software free and in the public domain
View the documentAnnex 2 Proposed surveillance definitions
View the documentAnnex 3 Role and use of Geographic Information Systems (GIS) and mapping for epidemiological surveillance

A00 Cholera

Case report universally required by International Health Regulations


Cholera causes an estimated 120 000 deaths per year and is prevalent in 80 countries. The world is currently experiencing the 7th pandemic. In Africa epidemics have become more frequent and case-fatality rates are high. Refugee or displaced populations are at major risk of epidemics due to the conditions prevailing in the camps (unsafe water, poor sanitation and hygiene). Control of the disease requires appropriate surveillance with universal case reporting. Health education of the population at risk and improvement of living conditions are essential preventive measures. Case reporting universally is required by the International Health Regulations.


Clinical case definition


In an area where the disease is not known to be present: severe dehydration or death from acute watery diarrhoea in a patient aged 5 years or more or

In an area where there is a cholera epidemic: acute watery diarrhoea, with or without vomiting in a patient aged 5 years or more*


* Cholera does appear in children under 5 years: however, the inclusion of all cases of acute watery diarrhoea in the 2-4 year age group in the reporting of cholera greatly reduces the specificity of reporting. For management of cases of acute watery diarrhoea in an area where there is a cholera epidemic, cholera should be suspected in all patients.

Laboratory criteria for diagnosis

Isolation of Vibrio cholerae O1 or O139 from stools in any patient with diarrhoea.

Case classification


Suspected: A case that meets the clinical case definition.
Probable: Not applicable.
Confirmed: A suspected case that is laboratory-confirmed.

Note: In a cholera-threatened area, when the number of "confirmed" cases rises, shift should be made to using primarily the "suspected" case classification.


Routine surveillance (this may be integrated with surveillance of diarrhoeal diseases: see acute watery diarrhoea).

Immediate case-based reporting of suspected cases from periphery to intermediate level and central level. All suspected cases and clusters should be investigated.

Aggregated data on cases should also be included in routine weekly/monthly reports from peripheral to intermediate and central level.


The initial suspected cases should be reported to WHO (mandatory).

Aggregated data on cases should be reported to WHO (mandatory).

Outbreak situations:


• During outbreak situations surveillance must be intensified with the introduction of active case finding
• Laboratory confirmation to be performed as soon as possible
• Thereafter weekly reports of cases, ages, deaths, regions, and hospital admissions to be set up


Case-based data for investigation and reporting


• Age, sex, geographical information
• Hospitalization (Y/N)
• Outcome

Aggregated data for reporting


• Number of cases by age, sex
• Number of deaths



• Use weekly numbers, not moving averages
• Case-fatality rates (graphs)
• Weekly/monthly plots by geographical area (district) and age group (GIS) (graphs)
• Comparisons with same period in previous five years



• Detect outbreaks, estimate the incidence and case-fatality rate
• Undertake appropriately timed investigations
• Assess the spread and progress of the disease
• Plan for treatment supplies, prevention and control measures
• Determine the effectiveness of control measures


At least one reference laboratory in each country is recommended for species identification.

Once the presence of cholera in an area has been confirmed, it becomes unnecessary to confirm all subsequent cases; shift should be made to using primarily the "suspected" case classification.

Monitoring an epidemic should, however, include laboratory confirmation of a small proportion of cases on a continuing basis.

For countries where cholera is rare or previously unrecognized, the first cases should be confirmed by laboratory diagnosis (including demonstration of toxigenic Vibrio cholerae O1 or O139 in faeces if possible).


Regional Offices

See Regional Communicable Disease contacts on section "Communicable disease contacts in Regional Offices".

Headquarters: 20 Avenue Appia, CH-1211 Geneva 27, Switzerland

Communicable Diseases Surveillance and Response (CSR)


E-mail: tikhomirove@who.ch / outbreak@who.ch
Tel: (41 22) 791 2624/2662/2111
Fax: (41 22) 791 4893/0746 attn CSR
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