Acute Watery Diarrhoea (AWD)

Acute watery diarrhoea is 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.

Suspected Cholera Case

In the absence of a probable or confirmed cholera outbreak

A suspected cholera case is 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.

In the presence of a probable or confirmed cholera outbreak

A suspected cholera case is any person:

• with acute watery diarrhoea; or
• who died from acute watery diarrhoea.

Confirmed Cholera Case

• A confirmed cholera case is any person infected with Vibrio cholerae O1 or O139, as confirmed by culture (including seroagglutination) or PCR.
• The bacterial strain should also be demonstrated as toxigenic (by PCR) if there is no confirmed cholera outbreak in other surveillance units, and no established epidemiological link to a confirmed cholera case or source of exposure in another country.

Community cholera death

• The death of a suspected or confirmed cholera case, with no other known cause of death, that occurs before reaching a health facility.

Health facility cholera death

• The death of a suspected or confirmed cholera case, with no other known cause of death, that occurs after arriving at a health facility.

Suspected cholera outbreak

A suspected cholera outbreak is detected when:

• Two or more suspected cholera cases; or
• One suspected cholera case with a positive RDT result (RDT+) • is/are reported in the same surveillance unit within seven days.

Probable cholera outbreak

• A probable cholera outbreak is detected when the number of suspected cholera cases with a positive rapid diagnostic test (RDT+) result achieves or surpasses a defined threshold within 14 days, while taking into account the number of suspected cases tested (see table below).

Confirmed cholera outbreak

A confirmed cholera outbreak is detected when a surveillance unit has at least one locally acquired, confirmed cholera case.

Community transmission

• Community transmission is the occurrence of confirmed cholera cases that are not all epidemiologically linked.
• Unless clustered transmission has been demonstrated through case investigation, an outbreak is classified as community transmission by default.

Clustered transmission

• Clustered cholera transmission is the occurrence of confirmed cholera cases that are all epidemiologically linked, based on the findings of case investigations.
• Clustered transmission is more likely to occur at the onset (or towards the end) of a cholera outbreak when the number of cholera cases is low.