Emerging Infectious Disease
Christine L. Case




Two children hospitalized with E. coli O157:H7 infection were reported to the Arizona Department of Health Services. Isolates from the two children had indistinguishable PFGE patterns. Both children had visited a zoo in Arizona that contained a petting zoo. No common food or beverage was consumed by the two children at the zoo, and the children were not related. One child had direct contact with petting zoo animals; the second child only had possible contact with exterior railings at the petting zoo. Both children had played in an area immediately adjacent to and downhill from the petting zoo facility. Fifteen of 25 (60%) fecal specimens from petting zoo animals yielded E. coli O157:H7; 12 isolates had PFGE patterns indistinguishable from the clinical isolates. Upon notification of the results, zoo officials immediately closed the petting zoo and adjacent play area.

Florida health officials identified a cluster of 22 E. coli O157:H7 infections, including seven hemolytic uremic syndrome cases, related to attendance at Florida Fairs and Festivals during February 10--21, 2005, and March 3--13, 2005. Early patient interviews identified no common food or water exposure but did implicate a common animal exposure (i.e., petting zoo attendance). Three implicated fairs had one common animal vendor, an exhibitor of a farm animal petting zoo. The petting zoo owner was contacted on March 24, and the animals (sheep, goats, and cattle) were placed under voluntary quarantine.

Petting-zoo associated E. coli O157 has been associated with direct animal contact (i.e., touching or feeding), indirect contact (e.g., touching sawdust or shavings) and exposure from contaminated clothes, shoes, strollers, or other fomites.

Petting zoo visits are popular leisure activities and also have become an important feature of education for children. The risk of visitors of petting zoos becoming infected with E. coli O157 from the livestock or the farm environment appears to be small, given the relatively small number of human cases each year in proportion to the large number of visitors. Cattle and other ruminants, such as sheep and goats, are important natural reservoirs of E. coli O157. It isn’t practical to try to exclude animals carrying E. coli O157 because they usually do not show clinical symptoms and shedding appears to be intermittent and transient. Colonization of cattle with E. coli O157 is typically of 2 months or less in duration. The CDC recommends that animal parks provide adequate handwashing stations and posted guidelines telling visitors to wash their hands after leaving animal areas.