Crossroads Farm Petting Zoo E. coli Outbreak - North Carolina
In late October 2004, the North Carolina Division of Public Health (NCDPH) received several reports of hemolytic uremic syndrome (HUS) among North Carolina residents who had attended the State Fair, which ran from October 14 to 24 in Raleigh, North Carolina. NCDPH recognized the potential for a large outbreak and immediately alerted local health departments, asking them to increase surveillance for diarrheal illnesses and requested epidemiologic support from the Centers for Disease Control and Prevention (CDC).
During the epidemiologic investigation, public health department investigators noted the relevance of fair and petting zoo attendance. Health officials soon refined their investigation further and began a case-control study in which a case was defined as a person with: a) laboratory confirmed E. coli O157:H7, b) a clinical diagnosis of HUS or Thrombotic Thrombocytopenic Purpura (TTP) diagnosed after October 15, 2004, or c) bloody diarrhea in a person who developed diarrhea after October 15 and who had attended the North Carolina State Fair between October 15 and November 7, 2004. A control was defined as a person who attended the State Fair between October 15 and 24 and did not develop diarrhea through November 11.
Investigators visited the state fairgrounds on several occasions and consulted with North Carolina Department of Agriculture and Consumer Services (NCDACS) fair officials regarding specific activities that might have factored in the outbreak. They obtained information about animals exhibited at the fair, areas where persons could have had direct contact with animals, and the layout of animals and pens in each of the animal areas. Livestock exhibits including goats, sheep, pigs, and cattle presented the greatest opportunity for fairgoers to have contact with animals. Animals were exhibited at 10 sites, including two commercial petting zoos, and two petting zoos.
Commerford and Sons Petting Zoo housed animals in pens. Visitors could reach over or through railings to touch the animals in this exhibit. Crossroads Farm Petting Zoo allowed persons to walk among and have extensive direct contact with sheep and goats. Both petting zoos allowed feeding. Hand sanitizer was available at both petting zoos. Neither erected handwashing facilities at or near the exhibit, though handwashing facilities certainly existed elsewhere on the fairgrounds.
Results of the outbreak investigation are reported in a document, “Outbreak of Shiga toxin producing E. coli (STEC) infection associated with a petting zoo at the North Carolina State Fair – Raleigh, North Carolina, November 2004,” dated June 29, 2005. In total, 108 cases of diarrheal illness were attributed to the outbreak. Of these, forty-one were laboratory confirmed with E. coli O157:H7, six were classified as probable cases, and 59 were classified as suspect cases. There were eighteen secondary cases. Fifty percent of the cases were under six years old. Ninety-three percent reported attending the fair and 89% reported petting zoo contact.
Thirty eight of the forty-one E. coli O157:H7 isolates obtained from cases shared an indistinguishable PFGE; these were designated Pattern A. The three remaining isolates demonstrated unique PFGE patterns and were classified as Patterns G, H, and J.
Eighteen of 96 environmental samples collected at the fairgrounds on November 3 were positive for E. coli O157:H7. Ten of fifteen samples obtained at the Crossroads Petting Zoo site were also positive. On November 9, investigators collected more samples at the Crossroads exhibit in areas where people could have direct contact with sheep and goats. Nineteen of these thirty samples were culture positive for E. coli O157:H7. All nineteen had PFGE patterns indistinguishable from Pattern A.
Investigators concluded that the case-control study, laboratory investigation, and environmental sampling consistently associated most outbreak illnesses with exposures at Crossroads Farm Petting Zoo. They attributed the exposures to three factors: 1) animals shedding E. coli O157:H7, 2) intensive and extensive contact with animals, and 3) behaviors associated with very young ages. Investigators further hypothesized that the high number of animals in the Crossroads Farm Petting Zoo area likely increased animal stress level, and some animals were noted by the owner of the Crossroads Farm Petting Zoo to have had loose stools.
Marler Clark represented four individuals who became ill with E. coli infections, some with hemolytic uremic syndrome, in claims against the North Carolina State Fair.