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E. coli
What is E. coli?
E. coli are bacteria that normally live in the intestines of humans and
animals. Although most strains are harmless, several are known to produce toxins that can
cause diarrhea. One particular E. coli strain called O157:H7 can cause severe
diarrhea and kidney damage.
Who gets E. coli O157:H7 infection?
Anyone of any age can become infected with E. coli O157:H7, but the very young
and the elderly are more likely to develop serious complications.
How is it spread?
E. coli O157:H7 can be acquired by eating contaminated food. The bacteria live
in the intestines of some healthy cattle and contamination of the meat may occur in the
slaughtering process. Deer meat (venison) may also be infected with the organism. Eating
meat that is rare or inadequately cooked is the most common way of getting the infection.
Fresh vegetables, unpasteurized fruit juices and raw milk have also caused
outbreaks. With careless food handling any food product eaten raw can be
contaminated by raw meat juices. Person-to-person transmission, especially in
child care settings, can occur if infected people do not wash their hands after
using the toilet or diapering children. Drinking contaminated water and swimming
in contaminated shallow lakes may also cause infection. Exposures have also
occurred from farm animals, particularly calves and cows, and deer jerky which
is uncooked dried meat.
What are the symptoms?
Some infected people have mild diarrhea or no symptoms at all. Most identified cases
develop severe diarrhea and abdominal cramps. Blood is often seen in the stool. Usually
little or no fever is present. Symptoms generally appear three to four days after
exposure, but can take as long as nine days to appear. Persons experiencing these symptoms
should contact their physician.
How is E. coli O157:H7 infection diagnosed?
Infection with E. coli O157:H7 can only be diagnosed by a special stool
culture that is not performed in all laboratories. Public health authorities advise
doctors and laboratories to consider performing a special stool culture test for
E.
coli O157:H7, particularly in people with bloody or severe diarrhea.
Laboratory tests can identify toxic-producing E.coli, but a culture
should also be done.
What is the treatment?
Symptoms generally go away without antibiotics or other specific treatment in five to
ten days. Studies suggest antibiotics are
harmful in the treatment of E. coli O157:H7 infection. It is recommended that
antibiotics and diarrhea medicines not be given.
What serious complications can result from E. coli O157:H7 infection?
In some people, particularly children under five years of age, the infection can cause
a complication called hemolytic uremic syndrome (HUS). This is a serious disease in which
red blood cells are destroyed and the kidneys fail. Transfusions of blood or blood
clotting factors, as well as kidney dialysis, may be necessary. A prolonged hospital stay
is often required. Fortunately, most people with HUS recover completely, but it can be
fatal.
What can I do to prevent infection?
Do not eat undercooked hamburger or other ground beef products. Cook roasts to at least
130 degrees F and other ground beef to 155 degrees F. Venison should be cooked to 165
degrees F. Make sure cooked ground beef is brown throughout (not pink) and the juices run
clear. Drink only pasteurized milk, milk products and fruit juices. Carefully wash all
produce, kitchen utensils and countertops. Wash hands carefully with soap after using the
toilet, changing a child’s diaper, or touching farm animals to reduce the risk of spreading disease. Wash
hands with hot, soapy water, rubbing hands together for 20 seconds. Persons ill
with diarrhea or children in diapers should not swim in pools or lakes.
Outbreaks
The largest Washington State E. coli O157:H7 outbreak was in 1993, when 477
people were infected from contaminated, undercooked hamburger. In 1994, 11 people were
infected from contaminated ground beef and also in 1994, 15 people were infected from
contaminated salami. Additional outbreaks have occurred in the United States from non-beef
sources including lettuce and salad bars where foods were contaminated by improperly
cleaned utensils, working surfaces and infected food handlers. In addition, outbreaks have
occurred in people who have consumed garden vegetables fertilized with animal manure,
unpasteurized apple cider, and home made venison jerky. Recently there have been cases due
to contaminated swimming water and petting farms.
Cases
Most E. coli O157:H7 infections are single cases and not associated with
outbreaks. The numbers of reported cases in Washington of E. coli O157:H7 peaked
in 1993 at 741 due to a large outbreak. Annually there are 150-300 cases in
Washington.
How can I get more information?
Contact the Food Safety Program at (360) 236-3385 or 1-888-586-9427, or Communicable Disease
Epidemiology at (206) 418-5500 or toll-free 877-539-4344.
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