Travel Medicine

E. coli

What is Escherichia coli O157:H7?

Escherichia coli O157:H7(or simply E. coli) is just one of the hundreds of strains of the bacterium Escherichia coli. Most strains of E. coli are harmless and live in the intestines of healthy humans and animals. E. coli, however, produces a powerful toxin that can cause a severe infection. (The combination of letters and numbers in the name of the bacterium refers to the specific markers found on its surface and distinguishes it from other types of E. coli.)

An estimated 10,000 to 20,000 cases of E. coli infection occur in the United States each year. The Centers for Disease Control and Prevention (CDC) recognizes E. coli as an emerging foodborne illness.

How is the E. coli infection spread?

Most E. coli illness has been associated with eating undercooked, contaminated ground beef. E. coli bacteria live in the intestines of healthy cattle and, although the number of organisms required to cause disease is not known, it is suspected to be very small. Meat becomes contaminated during slaughter, and organisms can be thoroughly mixed into beef when it is ground. Contaminated beef looks and smells normal. Other ways to transmit E. coli include:

Person-to-person contact in families and in child-care and other institutional-care centers can also be places where the transmission of the bacteria can occur.
Bacteria present on a cow's udders, or on equipment, may get into raw milk causing the infection.
Infection may also occur after swimming in or drinking sewage-contaminated water.
It has been confirmed that unpasteurized juices, such as apple cider, may also cause the infection.

What are the symptoms of an E. coli infection?

An E. coli infection can make a person very ill. The following are some of the most common symptoms associated with E. coli. However, each individual may experience symptoms differently, and some individuals may have no symptoms at all. Symptoms may include:

severe bloody diarrhea or non-bloody diarrhea
severe abdominal cramps

The symptoms of an E. coli infection may resemble other medical conditions. Always consult your physician for a diagnosis.

How is E. coli diagnosed?

E.coli 0157:H7 can be confirmed with a special stool culture.

What complications are commonly associated with an E. coli infection?

A complication called hemolytic uremic syndrome sometimes occurs, particularly in children under 5 years of age and the elderly. With this syndrome, the red blood cells are destroyed and the kidneys fail. Approximately 2 to 7 percent of infections lead to this complication, which is life threatening.

About one-third of people with hemolytic uremic syndrome have abnormal kidney function many years later.

According to the CDC, in the United States, hemolytic uremic syndrome is the principal cause of acute kidney failure in children, and most cases of hemolytic uremic syndrome are caused by E. coli.

How can an E. coli infection be prevented?

CDC recommendations for prevention of the infection include:

Cook all ground beef or hamburger thoroughly. Make sure that the cooked meat is gray or brown throughout (not pink), any juices run clear, and the inside is hot.
Using a digital instant-read meat thermometer, the temperature of the meat should reach a minimum of 160 degrees F.
If you are served an undercooked hamburger in a restaurant, send it back.
Consume only pasteurized milk and milk products. Avoid raw milk.
Consume only pasteurized juices and ciders.
Make sure that infected persons, especially children, wash their hands carefully and frequently with soap to reduce the risk of spreading the infection.
Drink municipal water that has been treated with adequate levels of chlorine, or other effective disinfectants.
Avoid swallowing lake or pool water while swimming.
Wash hands thoroughly after using the toilet.
People with diarrhea should not:
- swim in public pools or lakes
- bathe with others
- prepare food for others

This page was last updated on: February 14, 2008.

For patient inquiries, call 1-800-492-5538 or click here to make an appointment.