Enterotoxigenic E. coli (ETEC)


Escherichia coli (E. coli) is a type of bacteria that normally lives in the intestines of humans and animals. Most strains of E. coli are harmless and even beneficial for the digestion and absorption of nutrients. However, some strains of E. coli can cause infections and diseases in humans, such as urinary tract infections, sepsis, meningitis, and diarrhea.

Enterotoxigenic E. coli (ETEC) is one of the most common causes of bacterial diarrhea in developing countries and among travelers to these regions. ETEC is responsible for an estimated 840 million cases and 300,000 to 500,000 deaths annually, mainly in children under five years old. ETEC can also cause diarrhea in animals, such as pigs, calves, and lambs.

ETEC is characterized by the production of two types of toxins: heat-labile toxin (LT) and heat-stable toxin (ST). These toxins act on the intestinal cells and stimulate the secretion of fluids and electrolytes, resulting in watery diarrhea. ETEC strains may express LT only, ST only, or both LT and ST.

ETEC is transmitted by consuming food or water contaminated with animal or human feces that contain the bacteria. The infection usually occurs after ingesting a large number of bacteria (more than 10 million), which indicates poor sanitation and hygiene conditions. Person-to-person transmission is rare.

ETEC can be identified by detecting the LT and/or ST toxins in stool samples or cultures using immunoassays or PCR methods. ETEC strains belong to various serotypes based on their surface antigens (O and H antigens), but some serotypes are more frequently associated with human disease than others, such as O6, O8, O15, O25, O27, O153, and O159.

ETEC infection usually causes mild to moderate symptoms that last for 3 to 4 days. The main symptom is watery diarrhea, which may be accompanied by abdominal cramps, nausea, vomiting, fever, and dehydration. In some cases, especially in children, elderly people, and immunocompromised individuals, the infection can lead to severe dehydration, electrolyte imbalance, malnutrition, and death.

ETEC infection can be treated with supportive measures such as oral rehydration therapy (ORT) or intravenous fluids to prevent or correct dehydration. Antibiotics may be used in some cases to shorten the duration of symptoms and reduce bacterial shedding. However, antibiotic resistance among ETEC strains is a growing concern.

ETEC infection can be prevented by following safe food and water practices, such as boiling or treating water before drinking it; washing hands with soap before eating or preparing food; avoiding raw or undercooked foods; peeling fruits and vegetables; and using clean utensils and dishes. For travelers to high-risk areas, prophylactic antibiotics or vaccines may be considered, but their efficacy and availability are limited.

ETEC is a major public health problem that affects millions of people worldwide every year. It is a preventable disease that can be controlled by improving sanitation, hygiene, and access to safe water and food sources. It is also a target for vaccine development and research to reduce its burden and mortality.