Pathophysiology of diarrheal disorders

Travelers' diarrhea is only mild or moderate in the majority of cases. Consequently, severe fluid and electrolyte losses are encountered only rarely. Secretory, osmotic, and inflammatory processes in the intestine result in increased losses of fluid and electrolytes due to diarrhea. Disorders of intestinal motor activity, coupled with fluid secretion, may also have a role in causing an increase in the frequency of bowel movements. Several systemic symptoms, such as malaise, fatigue, anorexia, nausea, and fever, are commonly associated with diarrhea and contribute to significant morbidity, which is often sufficient to compromise effective participation in a vacation or business trip. Several putative mechanisms for the systemic symptoms associated with travelers' diarrhea are discussed in light of recent understanding of the enteric nervous system, intestinal neuropeptides and hormones, and other inflammatory mediators released from the bowel wall during enteric infections.