E. coli O157:H7 is one of many strains of the bacterium Escherichia coli
Most strains of E. coli are harmless and live in the intestines of healthy animals and humans. E. coli
O157:H7 is a strain of E. coli that produces a toxin and can cause severe illness.
People usually become infected with E. coli O157:H7 by eating contaminated food
The organism can live in the intestines of healthy cattle. Eating meat (especially ground beef) that is rare or
undercooked is the most common way of becoming infected. Drinking unpasteurized milk or juices, and
drinking or swimming in sewage-contaminated water can also cause infection. The bacteria are present in
an infected person's feces (stool) and may be spread from person to person.
E. coli O157:H7 can cause severe bloody diarrhea and abdominal cramps
Sometimes infection causes nonbloody diarrhea or no symptoms. Symptoms begin 3 to 4 days, but can
range from 1 to 10 days, after exposure. Hemolytic uremic syndrome (HUS) is a serious complication that
occurs in some infected people, particularly children under 5 and the elderly. In this syndrome, red blood
cells are destroyed and kidney failure occurs.
Infection can be diagnosed by detecting the bacterium in the stool
Your health care provider can request a special culture for E. coli O157:H7 from a laboratory.
See your doctor if you think you may have this infection
- Most people recover without specific treatment in 5 to 10 days. Fluid and electrolyte replacement is
important when diarrhea is watery or there are signs of dehydration. Antidiarrheal agents should be
avoided. Antibiotics may actually worsen the disease.
- HUS is a life-threatening condition that is usually treated in an intensive care unit.
- If foodhandlers, health care and child care workers, children in child care, or anyone in the family of such
people have an E. coli O157:H7 infection, they should contact their local health department to get
specific recommendations.
Infection with E. coli O157:H7 can be prevented by:
- Eating only thoroughly cooked meats and poultry (using a meat thermometer is the only way to ensure
that food is thoroughly cooked).
- Consuming only pasteurized milk and dairy products, and juices.
- Eliminating cross-contamination from raw foods to cooked ones by thoroughly washing cutting boards
and utensils, and by discarding used meat packages.
- Avoiding sewage-contaminated water.
- Washing all fruits and vegetables before eating.
- Washing your hands thoroughly with soap before and after handling foods, before eating, and after using
the toilet or changing diapers.
Maryland Department of Health & Mental Hygiene
Epidemiology & Disease Control Program
April 2008
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