Quick guide to protecting yourself from E. coli



The E. coli that are responsible for the numerous reports of contaminated foods and beverages are those that produce Shiga toxin, so called because the toxin is virtually identical to that produced by Shigella dysenteria type 1. The best-known and most notorious E. coli bacteria that produce Shiga toxin is E. coli O157:H7.

E. coli O157:H7 bacteria and other pathogenic E. coli mostly live in the intestines of cattle, but E. coli bacteria have also been found in the intestines of chickens, deer, sheep, and pigs.

Although foods of bovine origin (ground beef) are the most common cause of both outbreaks and sporadic cases of E. coliO157:H7 infections, outbreaks of illnesses have been linked to a wide variety of food items. For example, produce has been the source of substantial numbers of outbreak-related E. coli O157:H7 infections since at least 1991. Other vehicles for outbreaks include unpasteurized juices, yogurt, dried salami, mayonnaise, raw milk, game meats, hazelnuts, and raw cookie dough

In the US, documented outbreaks of non-O157 E. coli include 10 involving O111; 6 involving O26; 3 involving O45; 2 involving O145, O104, and O6; and one each involving O51; O103; O27; and O84. Non-O157 STEC outbreaks are rare but tend to primarily be due to contaminated food and person-to-person transmission.

The incubation period—that is, the time from exposure to the onset of symptoms—in outbreaks is usually reported as 3 to 4 days but may be as short as 1 day or as long as 10 days. Infection can occur in people of all ages but is most common in children.

As the infection progresses, diarrhea becomes watery and then may become grossly bloody; that is, bloody to the naked eye. E. coli symptoms also may include vomiting and fever, although fever is an uncommon symptom.

On rare occasions, E. coli infection can cause bowel necrosis (tissue death) and perforation without progressing to hemolytic uremic syndrome (HUS)—a complication of E. coli infection that is now recognized as the most common cause of acute kidney failure in infants and young children. In most infected individuals, symptoms of a Shiga toxin-producing E. coli infection last about a week and resolve without any long-term problems. Antibiotics do not improve the illness, and some medical researchers believe that these medications can increase the risk of developing HUS. Therefore, apart from supportive care, such as close attention to hydration and nutrition, there is no specific therapy to halt E. colisymptoms. The recent finding that E. coli O157:H7 initially speeds up blood coagulation may lead to future medical therapies that could forestall the most serious consequences. Most individuals who do not develop HUS recover within two weeks.

Since there is no fail-safe food safety program, consumers need to “drive defensively” as they navigate from the market to the table. It is no longer enough to take precautions only with ground beef and hamburgers; anything ingested by family members can be a vehicle for infection.

Shiga toxin-producing E. coli are so widely disseminated that a wide variety of foods can be contaminated. Direct animal-to-person and person-to-person transmission is not uncommon. Following are steps you can take to protect your family.

Be sure to clean and sanitize all imported and domestic fruits or vegetables. If possible, fruits should be skinned, or at least vigorously scrubbed and/or washed.

Vegetables (and of course meat) should be cooked to a core temperature of at least 160 degrees Fahrenheit for at least 15 seconds. If not cooked, fruits and vegetables should be washed to remove any dirt or other material, and then soaked in chlorinated water (1 teaspoon of household bleach in one quart of water, soaked for at least 15 minutes).

Be careful to avoid cross contamination when preparing and cooking food, especially if beef is being served. This requires being very mindful of the surfaces (especially cutting boards) and the utensils used during meal preparation that have come in contact with uncooked beef and other meats. This even means that utensils used to transport raw meat to the cooking surfaces should not be the same that are later used to remove the cooked meat (or other foodstuffs) from the cooking surfaces.

Do not allow children to share bath water with anyone who has any signs of diarrhea or “stomach flu”. And keep any toddlers still in diapers out of all bodies of water (especially wading and swimming pools). Do not let any family members touch or pet farm animals. Merely cleaning the hands with germ “killing” wipes may not be adequate! Wear disposable gloves when changing the diapers of any child with any type of diarrhea.

Remember that achieving a brown color when cooking hamburgers does not guarantee that E. coli bacteria have been killed. This is especially true for patties that have been frozen. Verifying a core temperature of at least 165 degrees Fahrenheit for at least 15 seconds is trustworthy.

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