Enterotoxigenic Escherichia coli (E. coli), or ETEC, is an important cause of bacterial diarrheal illness. Infection with ETEC is the leading cause of travelers’ diarrhea and a major cause of diarrheal disease in low and middle-income countries (LMIC), especially among children under the age of five.

What is ETEC?

Escherichia coli is a bacterium that normally lives in the intestines of humans and other animals. Most types of E. coli are harmless, but some can cause disease. ETEC bacteria is a group of E. coli which have the ability to colonise the small intestine via colonisation factors (CF/CS) antigens, and produce one or both of two toxins: heat-labile toxin (known as LT) and heat-stable toxin (ST). Over 25 CF/CSs have been identified, however a few CF/CSs dominate the clinical picture. The bacteria colonise the intestinal wall, allowing the bacteria to release toxins that stimulate the release of fluid and electrolytes causing diarrhoea.


ETEC infections

ETEC spreads through the faecal-oral route. Infection occurs when a person ingests foods or liquids contaminated with ETEC bacteria. Human wastes (e.g., faeces) are the ultimate source of ETEC contamination. Infection with ETEC can cause profuse watery diarrhoea and abdominal cramping. Fever, nausea with or without vomiting, chills, loss of appetite, headache, muscle aches and bloating can also occur but are less common. Illness develops 1-3 days after exposure. The most important determinant of risk is destination, and there are regional differences in both the risk for and aetiology of diarrhoea.


ETEC in travellers

Approx. 80 million travellers visit subtropical/ tropical countries annually. Traveling to Low- and Middle-Income Countries (LMIC) involves a risk of travel-related diseases. At least 35 million travellers per year are affected by travellers’ diarrhoea (TD). ETEC is the major cause of TD, responsible for approximately 15 million annual cases.

TD can ruin a significant part of a vacation or a business trip as symptoms usually continue up to 5 days but may last for 2 weeks or longer in 10% of cases. Between 3-17% of travellers, TD causes further health complications, including irritable bowel syndrome.



Diarrhea is the second-leading cause of death among children under the age of five worldwide. Globally, there are nearly 1.7 billion cases of childhood diarrheal disease every year leading to approximately 712 000 deaths in children below five years of age. ETEC is a major cause of diarrheal disease in children living in countries endemic for ETEC.

The link between a high diarrheal disease burden and poor physical and cognitive development among infants and young children in LMIC is so strong that many experts are beginning to consider diarrhea a form of acute malnutrition.