Infection and the gut.

Gastrointestinal symptoms, including vomiting, are caused by a variety of infective organisms in children, many of which are self-limiting and resolve within a week, but others are potentially much more serious in their consequences. Diarrhea, vomiting and abdominal pain are common but nonspecific symptoms. Investigation is dictated by the likely causative organism, given the age and presentation of the child. The role of bacteria in the pathogenesis of necrotizing enterocolitis, recognition that Yersinia, Campylobacter and Salmonella may produce symptoms difficult to distinguish clinically from appendicitis, the viral causes of idiopathic intussusception, the occurrence of intussusception after administration of rotavirus vaccine, and the evidence incriminating mycobacterium avium subspecies paratuberculosis in the aetiology of Crohn disease are discussed.