Infectious causes of chronic diarrhoea.

Infections are an uncommon cause of chronic diarrhoea. Parasites are most likely, including protozoa like giardia, cryptosporidia and cyclospora. Bacteria are unlikely to cause chronic diarrhoea in immunocompetent individuals with the possible exception of Yersinia, Plesiomonas and Aeromonas. Infectious diarrhoea can trigger other causes of chronic diarrhoea, including inflammatory bowel disease, irritable bowel syndrome and "Brainerd-type" diarrhoea. A thorough evaluation should detect most infections causing chronic diarrhoea.