Diarrhea is watery or liquid stools, usually with an increase in stool weight of more than 200 g daily and an increase in daily stool frequency.

• An estimated 4 billion cases of diarrhea occurred worldwide in 1996, resulting in 2.5 million deaths.

In persons from resource-poor countries, antisecretory agents (e.g., racecadotril) seem to be as effective at improving symptoms of diarrhea as antimotility agents (e.g., loperamide), but with fewer adverse effects.

• Empiric treatment with antibiotics also seems to reduce the duration of diarrhea and improve symptoms in this population, although it can produce adverse effects, such as rash, myalgia, and nausea.

• Instructing persons to refrain from consuming any solid food for 24 hours does not appear to be useful, although the evidence for this is sparse.

• We do not know how effective oral rehydration solutions or antibiotics plus antimotility agents are in persons from resource-poor countries because we did not find any randomized controlled trials.

Antisecretory agents, antibiotics, and antimotility agents also appear to be effective in treating persons from resource-rich countries who are traveling to resource-poor countries.

• We do not know whether antibiotics plus antimotility agents are more effective than either treatment alone or placebo.

• Bismuth subsalicylate is effective in treating traveler's diarrhea, but less so than loperamide, and with more adverse effects (primarily black tongue and black stools).

• We do not know the effectiveness of oral rehydration solutions or diet restriction in reducing symptoms of diarrhea in persons traveling to resource-poor countries.

For persons from resource-poor countries with mild or moderate diarrhea, antisecretory agents seem to be as beneficial as antimotility agents, and cause fewer adverse effects (particularly rebound constipation).

• We did not find sufficient evidence to judge the effectiveness of antibiotics, antibiotics plus antimotility agents, or oral rehydration solutions in this population.

Oral rehydration solutions are considered to be beneficial in persons from resource-poor countries who have severe diarrhea.

• Studies have shown that amino acid–based and rice-based oral rehydration solutions are beneficial, but the evidence is less clear about the effectiveness of bicarbonate or reduced osmolarity solutions.

We do not know whether intravenous rehydration is more beneficial than oral rehydration or enteral rehydration through a nasogastric tube.

• We do not know whether antimotility agents, antisecretory agents, antibiotics, or antibiotics plus antimotility agents are effective for treating persons in resource-poor countries who have severe diarrhea.

Definition

Diarrhea is watery or liquid stools, usually with an increase in stool weight of more than 200 g daily and an increase in daily stool frequency. This review covers empiric treatment of suspected infectious diarrhea in adults.

Incidence

An estimated 4 billion cases of diarrhea occurred worldwide in 1996, resulting in 2.5 million deaths. In the United States, the estimated incidence of infectious intestinal disease is 0.44 episodes per person every year (one episode per person every 2.3 years), resulting in about one consultation with a physician per person every 28 years. A recent community study in the United Kingdom reported an incidence of 19 cases per 100 person-years, of which 3.3 cases per 100 person-years resulted in consultation with a physician. Both estimates derive from population-based studies that included adults and children. The epidemiology of traveler's diarrhea is not well understood. The incidence is higher in travelers visiting resource-poor countries, but it varies widely by location and season of travel. The incidence of diarrhea in adults in resource-poor countries is largely unknown, owing to the lack of large-scale surveillance studies in these countries.

Etiology

The cause of diarrhea depends on geographic location, standard of food hygiene, sanitation, water supply, and season. Commonly identified causes of sporadic diarrhea in adults in resource-poor countries include Campylobacter, Salmonella, Shigella, Escherichia coli, Yersinia, protozoa, and viruses. No pathogen is identified in more than one half of persons with diarrhea. In returning travelers, about 50 percent of episodes are caused by bacteria, such as enterotoxigenic and enteroadherent E. coli, Salmonella, Shigella, Campylobacter, Vibrio, Yersinia, and Aeromonas.

Prognosis

In resource-rich countries, death from infectious diarrhea is rare, although serious complications, including severe dehydration and renal failure, can occur and may necessitate hospitalization. Older persons and those in long-term care have an increased risk of death. In resource-poor countries, diarrhea is reported to cause more deaths in children younger than five years than any other condition. Few studies have examined which factors predict poor outcome in adults.

editor's note: Racecadotril is not available in the United States.

search date: January 2007

Adapted with permission from de Bruyn G. diarrhoea in adults (acute). Clin Evid Handbook.