Petting Zoos May Spread E. coli

Proper Hygiene Needed to Prevent Infection

From the WebMD Archives

Aug. 21, 2002 -- Petting zoos may seem like a harmless way to let your child get close to farm animals, but new research shows that kind of closeness also comes with some risk.

A new study in the Aug. 22 issue of TheNew England Journal of Medicine shows that direct contact with animals is becoming an increasingly common cause of E. coli infection and illness for children.

Researchers from the CDC examined an outbreak of E. coli 0157:H7 infections among 51 children who visited a Pennsylvania dairy and petting farm in 2000. They found children who petted young calves directly were most likely to have become ill from the bacteria. But frequent hand washing seemed to protect against infection.

Various strains of the E. coli bacteria are found naturally in the stomach and bowels of people and animals, and most forms of the bug are harmless. But some strains, such as E. coli 0157:H7, can cause illness or even death when humans become infected with it.

In the case of the Pennsylvania dairy farm, a larger than normal portion of the calves and young cattle (13%) were infected with this dangerous form of E. coli and passed the bacteria along to the visitors.

The study authors say the bacteria can survive in the hides of the infected animals and their environment for months, which creates a risk of infection even without direct contact with animals.

That's why they recommend that all cattle be handled as if they were infected. In addition, all cattle environments, such as petting zoos, animal exhibits at fairs, and open farms, should be approached with caution as if they were contaminated with E. coli 0157:H7.

Researchers say this type of E. coli causes an estimated 60 deaths and 73,000 illnesses each year. Most of those cases are caused by contaminated food and water, but experts say they can be prevented through safe food handling and hygiene practices.

Meat, such as ground beef, can become infected with this dangerous strain of the bacteria during the production and packing process. Unpasteurized milk and juices also can harbor the harmful bacteria.


Although anyone can become infected, young children, the elderly, and people with weakened immune systems are most at risk.

In an editorial that accompanies the study, researchers say transmission of E. coli 0157:H7 from farm animals to humans is much more important than previously thought.

"These routes of transmission must therefore be considered along with transmission through food, water and direct person-to-person contact in any strategy for prevention," write Sarah J. O'Brien, FFPHM, and Goutam K. Adak, PhD, of the Public Health Laboratory Service Communicable Disease Surveillance Centre in the U.K.

Researchers say those prevention strategies should include:

  • Frequent hand washing after contact with livestock
  • Controlled and supervised contact with animals
  • Clear separation of food-related activities from areas housing animals

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