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Living > Public Health, Safety

E. coli Information

Facts and Information about E. coli

What is E. coli ?
Escherichia coli are bacteria that normally live in the intestines of humans and animals. Although most strains of this bacteria are harmless, several are known to produce toxins that can cause diarrhea.

One particular strain of E. coli called 0157:H7 can cause severe diarrhea and kidney damage. The combination of letters and numbers in the name distinguishes it from other types of E. coli.

E. coli 0157:H7 was first recognized as a cause of illness in 1982 during an outbreak of severe bloody diarrhea traced to contaminated hamburgers. Since then, most infections have come from eating undercooked ground beef and the disease has often been referred to 'hamburger disease'.

Outbreaks have been associated with apple cider (made from apples contaminated by cow manure), cheese, dry fermented meats and water (swimming in a crowded lake; drinking contaminated municipal water).

What are the symptoms?
E. coli 0157:H7 infection often causes severe bloody diarrhea and abdominal cramps; sometimes the infection causes mild diarrhea or no symptoms at all. Usually, little or no fever is present and the illness resolves in 5-10 days.

Anyone of any age can become infected with E. coli 0157:H7, but children are more likely to develop serious complications. In some persons, particularly children under 5 years of age and the elderly, the infection can also cause a complication called hemolytic-uremic syndrome (HUS), in which the red blood cells are destroyed and the kidneys fail. About 2-7% infections can lead to this complication.

How soon do symptoms appear?
Onset of symptoms begins 2-8 days after exposure, average 3-4 days.

How is it spread?
Foodborne infections are most commonly associated with contaminated beef products that are not thoroughly cooked before eating.

E. coli 0157:H7 bacteria live in the intestines of healthy cattle. Meat can become contaminated during slaughter, and organisms can be thoroughly mixed into beef when it is ground. Contaminated meat looks and smells normal. Bacteria present on the cow's udders or on equipment can also get into raw milk. Therefore, drinking unpasteurized milk can also cause infection.

Direct person-to-person transmission can occur by transfer of bacteria in stool of infected person from hands to mouth, especially if hand hygiene habits are inadequate. This is likely among toddlers who are not toilet trained. Family members and playmates of these children are at high risk of becoming infected. Waterborne transmission occurs both from contaminated drinking water and from recreational waters.

How long is a person contagious?
Persons infected with E. coli 0157:H7 continue to shed the bacteria in their stool for approximately one week or less in adults; up to 3 weeks in children. How is it diagnosed? Diagnosis is based on laboratory isolation of E. coli 0157:H7 bacteria from a stool specimen submitted for culture. All persons who suddenly have diarrhea with blood should get their stool tested for E. coli 0157:H7.

How is it treated?
Most persons recover without antibiotics in 5-10 days. Hydration is important. Antibiotics should not be used to treat this infection. There is no evidence that treatment with antibiotics is helpful, and taking antibiotics may increase the risk of HUS. Antidiarrheal agents like Imodium may also increase that risk.

How can E. coli be prevented?

  • Cook all ground beef thoroughly until no pink meat remains and the juices are clear
  • Clean and sanitize counter tops, cutting boards, utensils and dishes after contact with raw meat
  • If you are served undercooked hamburger in a restaurant, send it back
  • Thoroughly wash all fresh fruit and vegetables before eating
  • Drink only pasteurized milk and milk products; avoid unpasteurized apple cider
  • Drink water from a supply known to be safe; if you have a private water supply (well) it should be tested monthly; do not drink from open streams or lakes
  • People with diarrhea should not use recreational water venues (eg. Swimming pools, lakes, rivers, the ocean) for 2 weeks after symptoms resolve
  • Complete hand hygiene frequently to reduce the risk of spreading the infection
  • Have separate towels for sick people
  • Clean bathroom taps, toilets, and doorknobs at least once every day with an antiseptic cleaner such as bleach and water (1 part bleach to 10 parts water). Even better would be a separate bathroom for the sick person
  • Infected foodhandlers, patient care providers, childcare workers or children in daycare should be excluded from work/school until 2 successive negative stool cultures are obtained (collected 24 hours apart and not sooner than 48 hours after the last dose of antibiotics if used)

For more information, please contact Niagara Region Public Health, Infectious Disease Program at 905-688-8248 ext. 7330 or 1-888-505-6074.

This information is intended to provide general health-related information about E. coli 0157:H7. It is not intended to replace medical consultation by your physician and/or other health care professionals.

Sources: Red Book 2006, 27th Edition, American Academy of Pediatrics Control of Communicable Diseases Manual, 2004, 18th Edition, David L. Heymann


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