in nearly 3% of travellers who have returned from developing countries, diarrhoea persists for more than 14 days. In 1-2% of travellers diarrhoea persists for more than 14 days (1)
persistent diarrhoea is defined as diarrhoea lasting for 2-4 weeks (2)
aetiology of persistent diarrhoea varies according to the region (developing or developed), recent travel history, and the immune function of the underlying host.
infections are the commonest cause
enteropathogenic E. coli (EPEC) and enteroaggregative E. coli (EAEC) common in developing countries (Campylobacter and Salmonella are rare)
viruses (Norovirus and rotavirus) - common in developed countries especially in children
intestinal protozoa
Giardia and Cryptosporidium
Entamoeba and Isospora (1)
if a patient has employment which involves handling food then he/she should be advised to stay off work until the cause of persistent diarrhoea is identified and treated
if a case of dysentery is suspected then this should be notified
a clinician should consider the possibility of protozoa infection in cases of persistent diarrhoea e.g. G lamblia, E. histolytica
a stool sample should be sent (with travel history on the request form) for standard culture and microscopy for ova, cysts and parasits
if the stool sample is negative then empirical treatment with tinidazole or metronidazole has the advantage that it will treat pathogens such as G. lamblia which can be difficult to identify on stool examination
if a pathogen is isolated then appropriate antimicrobial treatment can be initiated
if diarrhoea is persistent despite treatment then specialist referral is appropriate e.g. to a gastroenterologist or infectious diseases specialist
possible further investigations include sigmoidoscopy and biopsy, serology for E. histolytica and Yersinia entercolitica, and, if necessary, small intestinal biopsy and microscopy of duodenal aspirate
Reference:
Drugs and Therapeutics Bulletin (2002), 40(5), 36-38.
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