Shiga toxin-producing E. coli (including E. coli O157:H7)

E. coli are bacteria that normally live in the intestines of humans and animals. There are many strains of E. coli bacteria and most of them are harmless. However, strains that produce Shiga toxin (such as E. coli O157:H7) can cause serious illness in people.

• Symptoms appear 1 to 10 days after exposure (usually within 2 - 4 days), and include: diarrhea (which often becomes bloody) and stomach cramps, with little or no fever.
• STEC infections are diagnosed by doing special tests on a stool sample from an ill person.
• An infected person may spread the illness to others by inadequate handwashing after a bowel movement.
• Antibiotics are not recommended for STEC infection because they can increase the risk of hemolytic uremic syndrome (HUS), a serious complication that damages the kidneys and blood vessels. Most cases of STEC don't develop HUS, which is more common in young children and the elderly.
• Shiga toxin-producing E. coli (STEC) can spread from cattle to people through raw or undercooked meat, unpasteurized milk, or contaminated water. People can also get infected by consuming raw produce or unpasteurized juice or cider that has been contaminated either by manure in the field or by raw beef or raw beef juices in the kitchen.

• E. coli factsheet (available in multiple languages)
• Questions and answers about E. coli (CDC)
• Health risks from consuming raw (unpasteurized) milk and milk products

• Epi-Log newsletter article on Shiga toxin-producing E. coli infections
• Shiga Toxin-Producing Escherichia Coli Infections: What Clinicians Need to Know (slides and audio from CDC)
• Recommendations for Diagnosis of Shiga Toxin-Producing Escherichia coli Infections by Clinical Laboratories (CDC)