Researchers from the CDC today release the results of a case-control study of an outbreak of
E. coli O157:H7 associated with two Florida petting zoos, in which they interviewed visitors who did and did not get sick to identify which behaviors were predictors of infection. Some behaviors that were most strongly associated with illness were feeding a cow or goat, touching a goat and stepping in manure or having manure on your shoes. Not surprisingly, simple handwashing after visiting the petting zoo, including lathering with soap and washing hands before eating and after visiting the petting zoo, were found to protect against infection.
"There is an increasing incidence of reported outbreaks of illness associated with petting zoos over the years. People need to be aware of these risks and take the appropriate precautions such as washing their hands after visiting," says Fred Angulo of the Centers for Disease Control and Prevention (CDC).
Unfortunately, according to two other studies being presented at the meeting this week, many visitors do not even engage in this simplest of preventive measures. Researchers from the South Carolina Department of Health and Environmental Control conducted an observational survey of visitors to a petting zoo at the 2005 South Carolina state fair. Despite the availability of numerous handwashing facilities and posted warnings regarding risk factors, approximately 28% of people observed exiting the petting zoo did not wash their hands.
In a similar survey, researchers from the Tennessee Department of Health monitored the use of hand-sanitizer stations at the exits of petting zoos in middle Tennessee. Of the 1,700 visitors, approximately 62% did not use the hand-sanitizer station after visiting the petting zoo.
Both studies also noted that a sizeable percentage of petting zoo visitors were also engaging in a number of other risky behaviors. The most common risky behavior observed by the South Carolina researchers was visitors bringing food or drink items into the petting zoo with them. In the Tennessee survey one in five visitors was observed eating or drinking in the petting zoo.
"Our petting zoo had a lot of signage warning of risk factors and people still brought in food and drink, failed to wash their hands and otherwise engaged in behaviors that put them at risk for infection," says Dan Drociuk, an author on the South Carolina survey.
Angulo notes that the lack of handwashing is not entirely the fault of the petting zoo visitors. "Most petting zoo visitors do not know that there is a risk and are not informed that there is a risk. Signs do not work. People need to be told by another human being to wash their hands."
To help address the risks associated with petting zoos, the CDC has entered a partnership with the National Association of State Public Health Veterinarians to develop a compendium of measures to prevent disease associated with animals in public settings. The compendium, which includes specific recommendations for managing contact between animals and people visiting a petting zoo environment, is published annually in the CDC publication Morbidity and Mortality Weekly Report. The 2005 compendium can be found online at http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5404a1.htm. The 2006 compendium will be published later this year.