Chronic diarrhea in travelers: diagnostic and therapeutic considerations.

Although the epidemiology, and pathophysiology of travelers' diarrhea are well understood, the long-term consequences of this syndrome are poorly appreciated. Many people struck with travelers' diarrhea do not completely recover but rather develop one of several chronic diarrheal syndromes. In some patients an episode of travelers' diarrhea seems to unmask a preexistent, underlying gastrointestinal disorder. The frequency of these complications and the magnitude of this problem are unknown. The differential diagnosis, diagnostic workup, and treatment of such patients have been outlined; unfortunately, many patients with chronic diarrhea elude diagnosis, and treatment is problematic. Some of the questions that must be answered include the following: What is the magnitude of the problem of chronic diarrhea following travelers' diarrhea? What is the natural history of patients with this syndrome? Which individuals are most likely to develop a chronic diarrheal syndrome, and can they be identified in advance? Are new etiologic agents involved in these chronic diarrheal syndromes? Answers to these questions will require well-organized, multicenter studies of a large number of travelers to various locales.