Shiga toxin-producing Escherichia coli (STEC)

Shiga toxin-producing Escherichia coli (STEC) is the term used to refer to a group of E. coli bacteria that can make toxins which can cause severe illness. Most STEC associated illnesses in North America are caused by E. coli O157:H7, but other serotypes of E. coli can also make Shiga toxins. The other most common Shiga toxin-producing serotypes in North America include O26, O111, O103, O45, and O121.

The period from ingesting the bacteria to feeling ill is called the “incubation period”. The incubation period for STEC ranges from one to ten days with an average of three to four days. The symptoms of STEC infections can vary but often include severe stomach cramps, diarrhea (often bloody), and vomiting. There is usually little or no fever, and most people get better within five to seven days. Some infections are very mild, but others are severe or even life threatening. Around 5% to 10% of those who are diagnosed with STEC infection develop a potentially life-threatening complication known as hemolytic uremic syndrome (HUS). The complication is serious and typically develops seven days (up to three weeks) after onset of diarrhea and results in death in approximately 3% to 5% of children.

Cattle are the most common reservoir of STEC; although sheep, deer, goats and other ruminants can carry the bacteria. A major source of exposure has been contaminated undercooked ground beef, but other foods have also been implicated, including unpasteurized milk and juice; and contaminated raw fruits and vegetables. Direct contact with animals and their environment is also a risk factor. Waterborne transmission has occurred through consumption of contaminated drinking water or recreational water that was inadequately chlorinated and from swallowing lake water while swimming. Person-to-person transmission occurs readily and can be difficult to control within families and in childcare facilities.

Tips for preventing the spread of this illness can be found on our tips page. To reduce the potential spread of STEC additional control measures may be required for persons associated with high-risk activities or settings such as food handlers, childcare facility personnel, and health care workers. Specific guidance and recommendations can be found in a manual titled Prevention and Control of Communicable Diseases. Additional guidance for retail food establishment management can be found in Chapter 2 of the food code.

For additional information on STEC, please visit the following references: Centers for Disease and Control and Prevention website and FDA’s Bad Bug Book. For data on reported STEC cases in Missouri visit the communicable disease data and statistical reports page for the annual reports listed there.