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Shiga toxin-producing E. coli (STEC)
Shiga toxin-producing Escherichia coli (STEC) is a reportable disease in Oklahoma. E. coli are among the most common bacteria found in the digestive tracts of humans and animals. While most strains of the bacteria are harmless, some strains have developed the ability to produce a toxin that can cause serious disease in humans. STEC including E. coli O157:H7 and other Non-O157:H7 strains such as O111, O26 and others can cause mild to severe diarrhea. In 1982, an unusual strain of E. coli (E. coli O157:H7) was identified as the cause of an outbreak of bloody diarrhea in the United States. E. coli O157:H7 is the most common of several strains of the toxin-producing bacteria called STEC.
E. coli O157:H7 and other STEC bacteria live in the digestive tracts of cattle and possibly other animals such as deer. Humans can become infected with the bacteria following direct or indirect contact with cattle feces. Indirect contact with the feces from cattle often results from eating contaminated foods. Serious outbreaks and deaths due to STEC have occurred in the U.S. resulting from undercooked ground beef, especially hamburgers. In addition, outbreaks have been linked to produce (melons, lettuce, coleslaw, and alfalfa sprouts), unpasteurized raw milk or juice, contaminated drinking or recreational water, and exposure to animals at petting zoos. The bacteria may also be spread from one person to another through feces, particularly within families, childcare centers, and other institutions.
The STEC bacterium causes diarrhea that is often bloody and accompanied by abdominal cramps, but fever is absent or mild. The illness typically resolves within a week. Unfortunately, about eight percent of individuals that experience symptoms due to STEC will develop hemolytic uremic syndrome (HUS). Persons who develop HUS may experience short-term kidney failure. However, some persons may develop long-term kidney failure, seizures, stroke, and damage to the bowel.
An estimated 2,100 hospitalizations and 61 deaths due to STEC occur annually in the U.S. Children under 5 years old are most frequently diagnosed with illness caused by STEC and are at greatest risk of developing HUS. The elderly also appear to be at increased risk of complications.
Most persons with disease caused by STEC will recover without antibiotics or other specific treatment within 5 to 10 days. There is no evidence that antibiotics improve the course of disease. Also, reasonable concern exists that some antibiotics may actually increase the risk of developing HUS. Antidiarrheal agents, such as loperamide (Imodium), should also be avoided. Health care providers may recommend an increased intake of fluids to prevent dehydration from STEC associated diarrhea. HUS is a life-threatening condition requiring hospitalization and treatment in an intensive care unit. Treatment for HUS often requires blood transfusions and kidney dialysis. Approximately three to five percent of persons who develop HUS will die despite treatment in intensive care.
Laboratory testing for the most common STEC, E. coli O157:H7, typically consists of identifying the bacteria in the stool of ill people. Most laboratories that culture stool do not routinely test for E. coli O157:H7, so it is important for health care providers to request that the stool specimen be tested on sorbitol-MacConkey (SMAC) agar for this bacteria. Commercial tests that can detect the toxin released by STEC bacteria have also been developed and should be included when a STEC is suspected. Persons who experience bloody diarrhea should seek medical attention and have their stool tested for STEC in addition to other enteric pathogens.
STEC Fact Sheets and Information:
STEC Hoja Informativa (194k.pdf)
Hemolytic Uremic Syndrome (HUS) Fact Sheets and Information:
HUS Fact Sheet (40k.pdf)
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