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, enterohemorrhagic E. coli, enterotoxigenic E. coli (ETEC), and enteropathogenic E. coli (EPEC) cause serious poisoning in humans. 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 are called Shiga toxin-producing E. coli (STEC).
E. coli O157:H7 has caused major disease outbreaks in North America. It is estimated that 70,000 cases of infection with E. coli O157:H7 occur in North America every year.
Cattle are the main sources of E. coli O157:H7, but these bacteria are also in other domestic and wild mammals. Most illness has been associated with:
- Contaminated food or water
- Contact with an infected person
- Contact with animals that carry the bacteria
The most common contaminated foods and liquids that have caused E. coli outbreaks include:
- Undercooked or raw hamburgers
- Produce such as spinach, lettuce, sprouted seeds
- Unpasteurized milk, apple juice, and apple cider
- Contaminated well water or surface water frequented by animals
STEC can also occur by
- Failure to wash your hands thoroughly with soap and water following contact with an infected animal or animal waste. This can occur at farms, petting zoos, fairs, or even in your own backyard
- Failure to wash your hands thoroughly with soap and water following contact with an infected person
- Swallowing unchlorinated or underchlorinated water in swimming pools contaminated by human feces
- Swimming in water with even very low levels of sewage contamination
- Consuming contaminated food, water, or ice
Shiga toxin-producing E. coli can cause bloody diarrhea and can lead to kidney failure, especially in young children or in people with weakened immune systems. Other symptoms include:
- Severe abdominal cramps
- Watery or very bloody diarrhea
STEC can also cause low-grade fever or vomiting. Symptoms usually begin from 2 to 5 days after eating contaminated food or drinking contaminated liquids. Symptoms may last for 8 days, and most people recover completely from the disease.
Early supportive treatment is important for people with E. coli infection, especially those who have Shiga toxin-producing E. coli.
There is no evidence that treatment with antibiotics is helpful, and taking antibiotics may increase the risk of hemolytic uremic syndrome, a serious complication of STEC that can lead to kidney failure.
To prevent Shiga toxin-producing E. coli infection, you should:
- Wash your hands thoroughly after going to the bathroom or changing diapers
- Wash your hands thoroughly after handling animals, animal bedding, or any material contaminated with animal fecal matter
- Eat only thoroughly cooked ground beef, pork, sheep meat, or sausage
- Cook ground meat products to an internal temperature of 160ºF
- Avoid drinking unpasteurized milk and juices
- Wash fresh fruits and vegetables thoroughly before eating raw
- Prevent cross contamination in food preparation areas by washing hands, counters, cutting boards, and utensils after they touch raw meat
- Keep raw meat separate from ready-to-eat foods
Hemolytic Uremic Syndrome
Hemolytic uremic syndrome, (HUS), a serious complication of Shiga toxin-producing E. coli, can lead to kidney failure and death. Children are particularly prone to this complication, and HUS is the most common cause of acute kidney failure In North America.
Blood transfusions and kidney dialysis, performed in the intensive care unit of a hospital, are needed to treat this life-threatening condition. About 8 percent of people with HUS have other lifelong complications, such as:
- High blood pressure
- The effects of having part of their intestines removed