The Florida State Fair outbreak was first recognized after two separate HUS case reports were posted on the Florida Department of Health EpiCom on March 18 and March 21, 2005. The two cases (a 5-yr-old girl and a 7-yr-old boy) both reported having visited a fair with a petting zoo (Agventure) a few days prior to becoming ill. The two children visited the same fair and did not have any other risk factors in common. The fair (the Central Florida Fair) was held from March 3-13, 2005.
The Orange CHD epidemiology on-call nurse was also contacted on March 20 by one of their local hospital administrators who reported a cluster of pediatric HUS cases in her hospital. Interviews with the parents of the hospitalized children revealed that all had attended a petting zoo (Agventure) at the Central Florida Fair or at a new fair (the Florida Strawberry Festival, also held March 3-13) within three weeks prior to becoming ill. E. coli O157:H7 isolates from the initial cases were sent to the Bureau of Laboratory in Jacksonville for PFGE typing (i.e., to determine if there was a match for the genetic fingerprints of the bacteria involved).
A conference call was held with county health department epidemiology staff in central and south Florida to discuss the initial results of the investigation, and to launch intensified E. coli O157:H7 case finding activities. A questionnaire with an extensive list of questions about potential risk factors for E. coli O157:H7 infections (including questions about exposures to foods, water and animals) was developed.
A list of animal vendors exhibiting at the Central Florida Fair and the Florida Strawberry Festival was obtained from management of the two fairgrounds. The two fairs had only one vendor in common, an exhibitor of a farm animal petting zoo (Agventure). The owner of Agventure was contacted on March 24, and the animals (sheep, goats and cattle) were placed under a voluntary quarantine for the duration of the outbreak investigation.
In conversations with the Agventure owner it was also revealed that the same animals had been exhibited once before, at the Florida State Fair, held between February 10-21, 2005.
An environmental investigation was undertaken at the three fair grounds and the Agventure petting zoo farm. Soil samples and environmental swabs were obtained from the petting zoo exhibit areas of the fairs. One hundred sixty eight animals exhibited at the fair, including the 37 animals exhibited at the farm animal petting zoo were also cultured.
The initial case definition was broad. As the outbreak investigation progressed, the case definition was made more specific and defined outbreak related cases by time, place and person as follows:
a. Confirmed-persons who attended one of the three fairs by 3/13/05 and had a lab diagnosis of E. coli O157:H7 within 10 days of fair attendance and/or had a lab diagnosis of HUS within 21days of fair attendance;
b. Suspect-persons who attended one of the three fairs and developed symptoms of E. coli O157:H7 within 10 days of fair attendance and/or developed symptoms of HUS within 21 days of fair attendance and did not have an alternative diagnosis; and
c. Secondary-persons who developed symptoms of E. coli O157:H7 and/or had a lab diagnosis of E. coli O157:H7 within 2-10 days of having close contact to a case or persons who developed symptoms of HUS and/or had a lab diagnosis of HUS within 21 days of having close contact to a case.
A total of 22 confirmed, 45 suspect and 6 secondary cases from 20 Florida counties were identified as victims of this outbreak. All but one culture-confirmed case had isolates with matching PFGE patterns. Most cases were infected at either the Central Florida Fair or the Florida Strawberry Festival (only 3 cases associated with the Florida State Fair). Twelve cases developed HUS. There were no fatalities.
E. coli O157:H7 with matching PFGE patterns were also recovered from the animal exhibit areas of the Central Florida Fair and the Florida Strawberry Festival. E. coli O157:H7 with matching PFGE patterns were also recovered from 6 animals from the Agventure petting zoo. See Excerpt from Florida Department of Health, EPI Update dated June 24, 2005.