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Fact Sheet


What is Escherichia coli O157:H7?

Escherichia coli ( E. coli) O157:H7 is a cause of diarrhea (frequent and watery bowel movements). E. coli O157:H7 is one of many of kinds of the bacterium Escherichia coli. Although most types of E. coli are harmless and live in the intestines (guts) of healthy humans and animals, the O157:H7 type produces a powerful toxin that can cause severe illness.

E. coli O157:H7 was first recognized as a cause of illness in 1982, during an outbreak of bloody diarrhea; that outbreak was traced to undercooked hamburgers.

How common are E. coli 157:H7 infections?

No one knows with any certainty. By one estimate,10,000 to 20,000 infections occur in the United States each year.


What are the symptoms of E. coli O157:H7 infection?

Infections can be very mild (even asymptomatic) or very severe, even fatal. E. coli O157:H7 typically causes diarrhea, often bloody, and often with vomiting or severe stomach cramps. Fever is usually very mild or nonexistent. Illness typically lasts two to ten days.


What are the complications of E. Coli O157:H7  infection?

In some persons, mostly young children, the infection can also cause hemolytic uremic syndrome, a kind of kidney failure. About 2% to 7% of reported infections lead to this problem. In the United States, hemolytic uremic syndrome is the principle cause of acute kidney failure in children, and most cases of hemolytic uremic syndrome are caused by E. coli O157:H7.


How is an E. coli O157:H7 infection diagnosed?

E. coli O157:H7 infection is diagnosed by stool culture (testing the bowel movement).


How is the illness treated?

Unfortunately, there is no one treatment that has been found to be effective against E. coli O157:H7, and it is possible that some antibiotics may increase the risk of problems. Anti-diarrheal agents, such as loperamide (Imodium®), should also be avoided. Some patients become dehydrated and may need IV fluids.

Hemolytic uremic syndrome is a life-threatening condition usually treated in an intensive care unit. Blood transfusions and kidney dialysis are often required. Even with intensive care, the death rate for hemolytic uremic syndrome is 3% to 5%. Some survivors may have permanent kidney and other problems.


How is E. coli O157:H7 spread?

E. coli O157:H7 is spread by eating undercooked meat (usually hamburger), drinking unpasteurized (raw) milk or juice, by swallowing polluted water (drinking water, pool water, rivers, lakes), or by eating hard-to-clean raw vegetables (like sprouts or lettuce) contaminated with the bacteria. It can also be spread from an infected person to another when hand washing is let.

The bacteria are common in herds of healthy cattle and have been found in deer, sheep, goats, and other animals. Meat or milk infected with animal waste can lead to disease, unless the bacteria are killed by cooking. Meat can become contaminated while being butchered. The bacteria may also be passed from the animal's waste to a nearby water source.


Are infected persons contagious?

Bacteria in bowel movements of infected persons can be passed from one person to another if hand washing is poor. This is most common among toddlers who are not potty-trained. After a person gets over the illness, they can continue to shed (get rid of) the bacteria through their bowel movements for several more weeks or even months. Some people who shed this bacteria may not have had any symptoms of illness, so hand washing is always important even when someone is not sick.


What can I do to prevent E. coli O157:H7 infection?

People can prevent many E. coli O157:H7 infections by thoroughly cooking meat, avoiding unpasteurized (raw) milk, and washing their hands carefully. Because the bacteria live in the guts of healthy cattle, deer and other animals, preventive measures on cattle farms and during meat processing are also being looked into.
Common ways to avoid getting E. coli O157:H7 infections are as follows:

  • Cook all meat thoroughly. Because ground beef can turn brown before disease-causing bacteria are killed, use a digital instant-read meat thermometer to ensure thorough cooking. Ground beef should be cooked until a thermometer reads at least 160°F. Be sure to insert the thermometer into several different parts of the patty, including the thickest part. To reduce the risk of illness without using a thermometer, do not eat ground beef patties that are still pink in the middle. If you get an undercooked hamburger or other ground beef product in a restaurant, send it back for further cooking. Make sure you get a new bun and a clean plate, too.
  • Treat game meat (for example, venison) with the same care used for store-bought meat.
  • Keep harmful bacteria out of your kitchen. Keep raw meat separate from ready-to-eat foods. Wash hands, counters, and utensils with hot soapy water after they touch raw meat. Never place cooked meat on the unwashed plate that held raw meat. Wash meat thermometers between testing of patties. Wash fruits and vegetables thoroughly, especially those that will not be cooked.
  • Drink only pasteurized milk, juice, and cider. Commercial juice with an extended shelf life sold at room temperature (juice in cardboard boxes, vacuum-sealed juice in glass containers, for example) has been pasteurized, although this is generally not shown on the label. Concentrated juices are also heated enough to kill bacteria.
  • Don't eat sprouts. Alfalfa, clover, and other kinds of uncooked sprouts are well-recognized potential sources for this and similar bacteria.
  • Don't drink water from rivers or streams, unless it has been treated.
  • Avoid swallowing lake or pool water while swimming. Don't let small children go into public swimming areas.

To reduce the risk of spreading infection, wash your hands carefully with soap and water after:

  • changing diapers,
  • handling meat.


If you have bloody diarrhea it is a good idea to contact your doctor or health clinic for information on where you can get tested. If you can't afford a doctor and/or are not currently on a health plan or insurance, call 1-800-SAFENET (723-3638) for information on low-cost clinics near you.


Issued by: The Oregon Health Services
Date: Published 11/98; Revised 12/99, 3/01. Return to top