Persistent diarrhoea in returned travellers

For persistent diarrhoea in returned travellers, consider both infective causes (eg Giardia duodenalis, Clostridioides difficile [formerly known as Clostridium difficile] if recently exposed to antibiotics) and noninfective causes (eg postinfectious irritable bowel syndrome, lactose intolerance, coeliac disease). A detailed travel history, including potential environmental exposures, can give important aetiological clues.

Investigations for persistent diarrhoea in returned travellers usually include microscopy and culture of stool samples. Multiple samples for microscopy to detect ova, cysts and parasites may be required to diagnose some parasitic infections, particularly those not identified by multiplex polymerase chain reaction (PCR) testingGefen-Halevi, 2022. Serology can be helpful in some cases (eg suspected amoebiasis, schistosomiasis or strongyloidiasis). In a large proportion of cases, a cause is not identified.

If the cause of symptoms is not identified, a trial of empirical therapy for giardiasis may be considered. If symptoms persist despite this, seek expert advice.