Enterotoxigenic Escherichia coli (ETEC) is a strain of E. coli that causes severe secretory diarrhea and subsequent dehydration and is most commonly seen in the developing world.

The diarrhea is mediated by a plasmid-encoded toxin that causes activation of adenylate / guanylate cyclase in the small bowel.

ETEC is a major pathogen causing diarrhea in the developing world and is responsible for a large percentage of childhood deaths from diarrhea in these countries. The majority of cases occur in children younger than 5 years. About 25% of cases occur in patients over 15 years. The organism is present in contaminated water. In developed countries, there have been rare foodborne outbreaks with ETEC, but most cases are seen in returning travelers.

As with cholera, the clinical presentation varies from asymptomatic or mildly symptomatic to severe diarrhea associated with severe dehydration. In general, ETEC illness is less severe than cholera. However, many cases in adults have cholera-like severe diarrhea. Malnourished children are also at risk for more severe disease.

The diarrhea is usually nonbloody. There is usually associated vomiting. Fever is typically absent. The illness is self-limited (lasting a few days), and if the patient is able to maintain sufficient hydration throughout the illness, mortality is very low.