Cholera Outbreak Toolbox

Cholera Outbreak Toolbox

Updated | September 2024

Welcome to the Cholera Outbreak toolbox

Key reference documents

Case definitions

Principles

  • Different case definitions apply depending on the prevailing cholera situation in a surveillance unit.
  • A surveillance unit corresponds to the lowest administrative level at which decisions are made to
    trigger cholera prevention and control measures and surveillance findings are used to inform local
    public health interventions. The corresponding administrative level is country specific and
    typically corresponds to administrative levels two or three. 
  • In surveillance units where there is no probable or confirmed cholera outbreak, using a more 
    specific definition (one that specifies the patient’s age and dehydration level) helps to avoid
    frequent, false suspected cholera cases/outbreaks from being detected, which could overwhelm
    the capacity of the surveillance system and decrease its effectiveness at early detection.

Case definitions

 In the absence of a probable or confirmed cholera outbreakIn the presence of a probable or confirmed cholera outbreak
Suspected cholera case

A person aged two years or older: 

  • with acute watery diarrhoea and severe dehydration; or
  • who died from acute watery diarrhoea with no other known cause of death.

Any person infected with acute watery diarrhoea or who died from acute watery diarrhoea.

Confirmed cholera case

Any person infected with Vibrio cholerae O1 or O139, as confirmed by culture (including seroagglutination) 
or PCR.

  
Acute watery diarhoea

An illness in which: 

  • Acute is defined as lasting less than seven days;
  • Watery is defined as non-bloody liquid stools that may contain mucous;
  • Diarrhoea is defined as three or more loose stools within a 24-hour period.

 

Outbreak definitions

Suspected cholera outbreak

Detection of at least one of the following:

  • Two or more suspected cholera cases or one suspected cholera case with a positive RDT result reported in a surveillance unit within seven days.  
  • The detection of a suspected cholera outbreak should trigger immediate public health measures for acute diarrhoeal diseases without waiting for laboratory confirmation of cholera.

 

Probable cholera outbreak 

When the number of suspected cholera cases with a positive rapid diagnostic test (RDT+) achieves or surpasses a defined threshold (see table below) within 14 days, while taking into account the number of suspected cases tested.

Number of RDT +out of # suspected cases tested
≥ 33-7
≥ 48-10
≥ 511-14
≥ 615-17
≥ 718-21

Confirmed cholera outbreak

A surveillance unit has at least one locally acquired, confirmed cholera case.

For more information on cholera case and outbreak definitions consult Public Health Surveillance for Cholera – Guidance Document 2024, Case & outbreak definitions (page x). 

 

Data collection tools

From Public Health Surveillance for Cholera – Guidance Document 2024 (GTFCC, 2024): 

Laboratory confirmation

All available resources are taken from the GTFCC resources webpage.