Acute infectious diarrhea in immunocompetent adults.

Copyright © 2014 Massachusetts Medical Society. I n the United States, approximately 179 million cases of acute diarrhea occur each year, amounting to 0.6 bouts per person per year. In one study, the estimated prevalence of diarrhea among adults the month before questioning was 3 to 7%, with the rate dependent on age, and 8% among children 5 years of age or younger.1 A similar rate of acute diarrhea among adults was reported recently in Germany.2 In the United States, 83% of deaths from acute diarrhea occur in adults 65 years of age or older. Hospital-associated Clostridium difficile– associated diarrhea is the most prevalent cause of fatal illness, followed by norovirus infection3; both are common in residents of nursing homes.4 Diarrhea is generally defined as the passage of three or more unformed stools per day, often in addition to other enteric symptoms, or the passage of more than 250 g of unformed stool per day. On the basis of its duration, diarrhea can be classified as acute (<14 days), persistent (14 to 29 days), or chronic (≥30 days). Gastroenteritis, which is often due to viral infection involving the stomach and small intestine, is associated with vomiting and diarrhea. This review addresses the clinical approach to the diagnosis and management of acute diarrhea in immunocompetent adults, summarizes contemporary clinical controversies, and discusses research needed in the field.