Cause
While there are many types of E. coli bacteria, only certain types cause foodborne illness. Hundreds of harmless strains of E. coli can be found widely in nature, including the intestinal tracts of humans and other warm-blooded animals. Disease-causing strains, however, are a frequent cause of both intestinal and urinary-genital tract infections.
In 1982, scientists identified the first harmful foodborne strain of E. coli in the United States. The disease-causing foodborne E. coli most commonly found in this country is called O157:H7, which refers to chemical compounds found on the bacterium’s surface. Cattle are the main sources of E. coli O157:H7, but these bacteria also can be found in other domestic and wild mammals.
Several different strains of harmful E. coli can cause diarrheal disease.
- Particularly dangerous types of E. coli, such as E. coli O157:H7, produce one or more kinds of toxins (poisons) called Shiga toxins. Shiga toxins can severely damage the lining of your intestines and kidneys. These types of bacteria are called Shiga toxin-producing E. coli (STEC). STEC often causes bloody diarrhea and can lead to kidney failure in children or in people with weakened immune systems.
- Enterotoxigenic E. coli (ETEC), which produce a different toxin, can cause diarrhea. These strains typically cause so-called travelers’ diarrhea because they commonly contaminate food and water in developing countries.
- Enteropathogenic E. coli (EPEC) cause persistent diarrhea (lasting 2 weeks or more) and are more common in developing countries where they can be transmitted to humans through contaminated water or contact with infected animals.
Other types of E. coli, including O26:H11 and O111:H8, also have been found in the United States and can cause disease in people.
back to top