National Institute of Allergy and Infectious Diseases
Escherichia coli (E. coli) Hundreds of E. coli strains are harmless, including those that thrive in the intestinal tracts of humans and other warm-blooded animals. These strains are part of the protective microbial community in the intestine and are essential for general health. Other strains, such as E. coli serotype O157:H7, cause serious poisoning in humans. Cattle are the main sources of E. coli O157:H7, but these bacteria also are also in other domestic and wild mammals. E. coli O157:H7 has caused major disease outbreaks in the United States. The Centers for Disease Control and Prevention estimates 70,000 cases of infection with E. coli O157:H7 occur in this country every year. In 2007, it accounted for about 7% of gut-related diseases reported to health agencies in the United States. In addition to E. coli O157:H7, there are other serotypes of E. coli, named enterohemorrhagic E. coli, that cause the same serious illnesses. E. coli O157:H7 can produce one or more kinds of poisons that can severely damage the lining of the intestines and kidneys. These types of bacteria, called Shiga toxin-producing E. coli (STEC), often causes bloody diarrhea and can lead to kidney failure, especially in young children or in people with weakened immune systems. Most illness has been associated with contaminated food or water, contact with an infected person, or contact with animals that carry the bacteria. Other forms of E. coli that cause diarrheal disease include: Enterotoxigenic E. coli (ETEC) is a leading bacterial cause of diarrhea in the developing world. Each year, about 210 million cases and 380,000 deaths occur, mostly in children, from ETEC, according to the World Health Organization. ETEC is the most common cause of traveler’s diarrhea and affects troops on deployment overseas. Enteropathogenic E. coli (EPEC) is a bacterial cause of persistent diarrhea that can last 2 weeks or more. It spreads to humans through contact with contaminated water or infected animals and is common in developing countries. In industrialized countries, the frequency of these organisms has decreased, but they continue to be an important cause of diarrhea, according to CDC.