Escherichia coli (E. coli) bacteria normally live in the intestines of healthy people and animals. Most varieties of E. coli are harmless or cause relatively brief diarrhea. But a few particularly nasty strains, such as E. coli O157:H7, can cause severe abdominal cramps, bloody diarrhea and vomiting.
You may be exposed to E. coli from contaminated water or food — especially raw vegetables and undercooked ground beef. Healthy adults usually recover from infection with E. coli O157:H7 within a week, but young children and older adults have a greater risk of developing a life-threatening form of kidney failure called hemolytic uremic syndrome.
Signs and symptoms of E. coli O157:H7 infection typically begin three or four days after exposure to the bacteria, though you may become ill as soon as one day after to more than a week later. Signs and symptoms include:
Contact your doctor if your diarrhea is persistent, severe or bloody.
Among the many strains of E. coli, only a few trigger diarrhea. One group of E. coli — which includes O157:H7 — produces a powerful toxin that damages the lining of the small intestine, which can cause bloody diarrhea. You develop an E. coli infection when you ingest this strain of bacteria.
Unlike many other disease-causing bacteria, E. coli can cause an infection even if you ingest only small amounts. Because of this, you can be sickened by E. coli from eating a slightly undercooked hamburger or from swallowing a mouthful of contaminated pool water.
Potential sources of exposure include contaminated food or water and person-to-person contact.
The most common way to acquire an E. coli infection is by eating contaminated food, such as:
Human and animal feces may pollute ground and surface water, including streams, rivers, lakes and water used to irrigate crops. Although public water systems use chlorine, ultraviolet light or ozone to kill E. coli, some outbreaks have been linked to contaminated municipal water supplies.
Private wells are a greater cause for concern because they don't often have any disinfecting system. Rural water supplies are the most likely to be contaminated. Some people also have been infected after swimming in pools or lakes contaminated with feces.
E. coli bacteria can easily travel from person to person, especially when infected adults and children don't wash their hands properly. Family members of young children with E. coli infection are especially likely to acquire it themselves. Outbreaks have also occurred among children visiting petting zoos and in animal barns at county fairs.
E. coli can affect anyone who is exposed to the bacteria. But some people are more likely to develop problems than are others. Risk factors include:
Most healthy adults recover from E. coli illness within a week. Some people — particularly young children and older adults — may develop a life-threatening form of kidney failure called hemolytic uremic syndrome.
No vaccine or medication can protect you from E. coli-based illness, though researchers are investigating potential vaccines. To reduce your chance of being exposed to E. coli, avoid risky foods and watch out for cross-contamination.
Cook hamburgers until they're 160 F. Hamburgers should be well-done, with no pink showing anywhere in the meat. But color isn't a reliable indicator of whether or not meat is done cooking. Meat — especially if grilled — can brown before it's completely cooked.
That's why it's important to use a meat thermometer to ensure that meat is heated to at least 160 F (71 C) at its thickest point.
To diagnose illness caused by E. coli infection, your doctor will send a sample of your stool to a laboratory to test for the presence of E. coli bacteria. The bacteria may be cultured to confirm the diagnosis and identify specific toxins, such as those produced by E. coli O157:H7.
For illness caused by E. coli, no current treatments can cure the infection, relieve symptoms or prevent complications. For most people, treatment includes:
Avoid taking an anti-diarrheal medication — this slows your digestive system down, preventing your body from getting rid of the toxins. Antibiotics generally aren't recommended because they can increase the risk of serious complications.
If you have a serious E. coli infection that has caused hemolytic uremic syndrome, you'll be hospitalized and given supportive care, including IV fluids, blood transfusions and kidney dialysis.
Follow these tips to prevent dehydration and reduce symptoms while you recover:
Most people don't seek medical attention for E. coli infections. If your symptoms are particularly severe, you may want to visit your primary care doctor or seek immediate care.
Here's some information to help you get ready for your appointment and know what to expect from your doctor.
For E. coli, some basic questions to ask your doctor include:
Your doctor may ask:
If you or your child has an E. coli infection, it may be tempting to use an anti-diarrheal medication, but don't. Diarrhea is one way the body rids itself of toxins. Preventing diarrhea slows that process down.
Take small sips of fluid as tolerated to try to stay hydrated.