Differentials
Other infectious diarrhoea
SIGNS / SYMPTOMS
Many causes of infectious diarrhoea will be impossible to differentiate from cholera, especially in the early stages of disease or mild cases.
Bloody diarrhoea is suspicious for Shigella or enterohaemorrhagic Escherichia coli.
INVESTIGATIONS
Stool culture is the standard, but some techniques (e.g., for Campylobacter) are difficult and not performed in resource-limited settings.[91]
Polymerase chain reaction for toxins helps to distinguish enterohaemorrhagic E coli.
For a returning traveller work-up, broader testing of stool (and blood) for enteric pathogens through molecular and/or serology may be considered.
Amoebic dysentery
SIGNS / SYMPTOMS
Volume of diarrhoea rarely exceeds 1 litre/hour for adults.
Bloody diarrhoea common.
INVESTIGATIONS
Fresh stool microscopy shows amoebae ingesting red blood cells.
Strongyloides and other intestinal helminths
SIGNS / SYMPTOMS
Rare to have large-volume stool loss.
INVESTIGATIONS
Stool microscopy for eggs and live parasites requires training and good equipment to detect Strongyloides stercoralis.
Giardiasis
SIGNS / SYMPTOMS
Giardiasis often causes offensive, yellow, sulfur-scented stools.
Rare to have large-volume stool loss.
INVESTIGATIONS
Stool microscopy for eggs and live parasites requires training and good equipment to detect Giardia.
VIPoma
SIGNS / SYMPTOMS
Volume of diarrhoea rarely exceeds 1 litre/hour.
Chronic history.
Much rarer than cholera.
INVESTIGATIONS
Fasting gut hormone analysis confirms diagnosis.
Negative stool culture for cholera.
Tubulovillous adenoma
SIGNS / SYMPTOMS
Volume of diarrhoea rarely exceeds 1 litre/hour.
Chronic history of diarrhoea.
Much rarer than cholera.
INVESTIGATIONS
Colonoscopy and biopsy of lesions shows adenoma.
Negative stool culture for cholera.
Food poisoning
SIGNS / SYMPTOMS
Volume of diarrhoea rarely exceeds 1 litre/hour.
INVESTIGATIONS
Stool white blood cell count may help differentiate invasive or inflammatory diarrhoea.
Stool culture may help isolate specific pathogens.
Other medical causes of diarrhoea
SIGNS / SYMPTOMS
Guided by medical history, drug history, presenting illness and medical examination, and laboratory tests.
INVESTIGATIONS
Returning traveller work-up, also to include test for malaria (may cause non-specific symptoms such as diarrhoea).
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