There are many strains of the bacteria Escherichia coli (E. coli). Most strains are harmless and live in the intestines of healthy humans and animals. Some kinds of E. coli cause disease by producing Shiga toxin.
The bacteria that make these toxins are called "Shiga toxin-producing" E. coli (STEC). The most commonly found STEC in the United States is E. coli O157:H7.
The symptoms of STEC infections can include:
Some infections are mild, but others can be life-threatening.
The CDC estimates that 265,000 STEC infections occur each year in the United States. E. coli O157:H7 causes more than 36 percent of these infections. People of all ages can be infected, but young children and the elderly are more likely to develop severe symptoms.
The types of E. coli that can cause illness can be transmitted through contaminated water or food, or through contact with animals or people.
To avoid E. coli infections, experts advise to thoroughly cook meat, avoid unpasteurized dairy products and juices, avoid swallowing water while swimming, and wash hands regularly.