During 2004 to 2005, there were 3 outbreaks of Escherichia coli infections among agricultural fair, festival, and petting zoo visitors in North Carolina, Florida, and Arizona.
Dr Davis and colleagues investigated these outbreaks and submitted a report.
The research team reported that there were 108 cases, including 15 cases of hemolytic uremic syndrome, in the North Carolina outbreak.
| Illnesses primarily affected children who visited petting zoos|
|Journal of the American Medical Association|
The team noted that 63 cases, including 7 hemolytic uremic syndrome cases, were reported in the Florida outbreak.
A further 2 cases were reported in Arizona.
The researchers reported that no fatalities occurred.
Illnesses primarily affected children who visited petting zoos at these events.
The median age was 5 years and 59% were female.
In total, 20 patients were hospitalized.
The North Carolina Division of Public Health conducted a case-control study to identify risk factors for infection.
The researchers enrolled 45 case-patients and 188 controls.
The participants were frequency-matched to cases in 3 age groups, between 0 and 5 years, 6 and 17 years, and 18 years.
Potential controls were identified from a randomized list of 23,972 who attended the fair, and reported no diarrhea through 2004.
The study questionnaire included items about human or animal interactions, food and beverage consumption, and hygiene practices.
The researchers computed adjusted odds ratios and 95% confidence intervals for various exposure variables.
The researchers found that no specific food, beverage, or recreational water exposure was associated with illness.
Infection appeared to be related to extensive environmental contamination, where visitors could have extensive contact with animals and their bedding.
Case-patients reported spending a median of 20 minutes the petting zoo, compared with 15 minutes for controls.
Among children aged less than 6 years who visited the petting zoo, illness was associated with touching or stepping in manure.
Behaviors such as falling or sitting on the ground was associated with the illness.
The researchers noted that the use of a pacifier or "sippy" cup or sucking on one's thumb while in petting zoo B also were associated with illness.
Reported alcohol-based hand sanitizer use was not protective.
However, reported awareness of risk for disease from contact with livestock among adults accompanying the children, was protective.
In the North Carolina outbreak, extensive direct animal contact occurred in an area contaminated with manure.
In the Florida outbreak, illness was associated with touching and feeding animals and indirect animal contact, such as touching sawdust.
In the Arizona outbreak, at least 1 case likely resulted from exposure in the play area adjacent to the petting zoo.
In Arizona, contamination via drainage from the petting zoo was suspected.
The researchers suggest that in certain instances, exposure to E coli might have occurred before petting zoo patrons could practice hand hygiene.
Also, exposure from contaminated clothes, shoes, strollers, or other fomites might have occurred before or after hand-hygiene practice.
Dr Davis and colleagues concluded, “This report summarizes findings from these outbreak investigations."
"These findings indicate the need for adequate control measures to reduce zoonotic transmission of E coli."