Outbreak of Shiga Toxin--Producing Escherichia coli O157 Infection Associated with a Day Camp Petting Zoo --- Pinellas County, Florida, May--June 2007

On June 7, 2007, the Pinellas County Health Department in central Florida was notified by a private physician regarding a positive laboratory result for Shiga toxin--producing Escherichia coli O157 (STEC O157) infection in a child aged 9 years. Initial interviews revealed the child had attended a week-long session at a day camp and had come into contact with animals in the camp's petting zoo. On June 8, an investigation was begun by the Pinellas County Health Department; the same day, the petting zoo was closed on the recommendation of the health department. This report summarizes the results of the investigation, which identified seven cases of STEC O157 infection: four laboratory-confirmed primary cases, two probable primary cases, and one laboratory-confirmed secondary case, all associated directly or indirectly with the petting zoo. Two children were hospitalized; all seven patients recovered. Petting zoo operators should adhere to guidelines for supervised handwashing and other prevention measures that will help minimize the risk in children for infection from animal contact.

The day camp conducted 13 week-long sessions from May 21 through August 17, with 45 children in grades 2--8 per session. A petting zoo on the premises included a 2,250 square-foot enclosed animal interaction area with 28 goats, one sheep, and one llama. Children brought their own lunches and snacks to the camp each day. Meals were eaten inside a building during scheduled hours and were not consumed in the petting zoo area. Investigators learned that campers and staff members fed the animals and had unlimited access to the animals through a single combined entry and exit. Animal contact was encouraged throughout the day, from 8 a.m. until the camp closed at 5 p.m. Staff members were responsible for maintaining and cleaning the animal area and bathing the animals.

Initial investigation determined that handwashing facilities, signage, and hand hygiene compliance generally adhered to recommendations of the National Association of State Public Health Veterinarians (NASPHV) for contact with animals in public settings (1). Four handwashing facilities with liquid soap, running water operated by a foot pedal, and disposable towels were located outside the enclosed animal area near the entry/exit. Signs notified visitors that no food or drink was allowed in the animal area and that visitors should wash their hands upon leaving the area. In addition, signs on each handwashing facility instructed campers in handwashing. At least one staff member was required to be present near the zoo exit to instruct campers to wash their hands and direct them toward handwashing facilities. However, campers were not instructed in appropriate handwashing technique, and the staff member was stationed too far from the handwashing facilities to observe handwashing behavior.

A probable case of STEC O157 infection was defined as illness in a person with onset during May 25--June 12 of symptoms of diarrhea (i.e., three or more loose stools per 24-hour period) and any of three other symptoms (i.e., abdominal cramping, nausea, or vomiting) but no laboratory confirmation. A confirmed case was defined as a probable case with laboratory confirmation. A primary case was defined as confirmed or probable STEC O157 infection in a patient who attended a day camp session. A secondary case was defined as confirmed or probable STEC O157 infection in a patient who did not attend a day camp session but who was linked epidemiologically to a primary case.

A list of the 135 children aged 7--13 years who attended the first three sessions of the day camp (May 21--25, May 28--June 1, and June 4--8) and the 10 persons who staffed the camp sessions was obtained from the camp director. To identify any additional cases of diarrheal illness associated with attendance at the day camp, parents of 117 (87%) campers were contacted by telephone. Among those 117 campers, two persons with diarrhea, aged 8 and 10 years, met the case definition for probable STEC O157 infection. On June 11, the physician who reported the initial case reported a secondary confirmed case of STEC O157 infection in a boy aged 3 years who had not attended the day camp but became ill after a sibling who attended the camp developed symptoms. During June 14--15, a local hospital reported three additional primary laboratory-confirmed cases in children aged 7, 9, and 12 years who had attended or worked at the day camp. Two of the three children had been hospitalized, and one had been treated in the emergency department.

Symptoms reported in the seven cases were diarrhea with bloody stools (four patients), diarrhea without bloody stools (three), abdominal cramping (four), nausea (two), vomiting (two), and fever (two). Onset of illness among the seven ranged from May 29 to June 11 (Figure). One of the four campers with a confirmed case had attended the camp for the first session, one camper with a confirmed case and the two with probable cases had attended the second session, and one camper with a confirmed case had attended the third session. The other person with confirmed STEC O157 infection was a staff volunteer aged 12 years who had worked at the camp during all three sessions.

All four campers with primary confirmed cases reported contact (e.g., petting, carrying, and feeding) with the petting zoo animals. Direct contact with the animals also was reported by a camper with probable infection; whether the second camper with probable infection had animal contact was unknown. Investigation revealed no common food, beverage, or recreational water exposures that might account for the STEC O157 infections.

Stool specimens from five of the seven children were collected during May 31--June 12. Specimens from the 30 zoo animals and four soil samples from the grounds of the petting zoo were collected by the Florida Department of Agriculture and Consumer Services on July 23. Four human clinical isolates of E. coli O157:NM (nonmotile), nine isolates from goats, and all four soil isolates had an identical pulsed-field gel electrophoresis (PFGE) pattern (EXHX01.0202) when tested at the Florida Public Health Laboratory. The PFGE pattern did not match any of the 30 other STEC O157 strains collected in Florida's E. coli database in 2007 and did not match any of the strains in the CDC PulseNet database. One isolate from a goat had a different PFGE pattern from the human clinical isolates.

On June 8, the first day of the Pinellas County Health Department investigation, the petting zoo was closed on the recommendation of the county health department. The zoo animals were placed under quarantine for E. coli O157:NM colonization. Subsequently, no additional cases of STEC O157 infection were reported among campers or staff members.

Reported by: KA Alelis, MPH, PE Borkowski, Pinellas County Health Dept; P Fiorella, PhD, J Nasir, J Middaugh, MD, C Blackmore, DVM, Florida Dept of Health. J Keen, DVM, US Dept of Agriculture and Univ of Nebraska.

Editorial Note:

In a 1999 report, STEC O157:H7 was estimated to cause 73,000 illnesses in the United States annually (2). The disease spectrum ranges from nonbloody diarrhea to hemolytic uremic syndrome (3). STEC O157 infections generally are self-limiting; however, an estimated 2,000 patients are hospitalized, and 60 die from the infection each year (2). Asymptomatically colonized domestic ruminants are the primary animal reservoir hosts. The organisms usually are found in an animal's gastrointestinal tract but also can be isolated from the hide and oral cavity (4). STEC O157 is transmitted via multiple routes, including foodborne and laboratory exposure, person-to-person, or animal contact. Laboratory and epidemiologic evidence in this outbreak suggest the STEC O157 infections were attributable either to direct contact with animals and their petting zoo environment or indirect contact, possibly via contaminated clothing, which has been identified as a risk factor for E. coli O157 infection in previous petting zoo outbreaks (1). Person-to-person transmission at the day camp was unlikely because of the small number of cases spread over the three 1-week camp sessions. Possible reasons for the small number of cases include the immediate closure of the petting zoo and the handwashing requirements in effect.

The outbreak in this report is unlike previous outbreaks in petting zoos because transmission of STEC O157 occurred even though prevention measures were being used to reduce the risk for disease (5). Several studies have found handwashing with soap and water decreases the risk for E. coli O157 infection (5). In addition, the campers were school aged, able to read the handwashing signs and follow directions, and probably lacked some hand-to-mouth behaviors that place younger children at risk for infection (1). However, this outbreak also illustrates that even when prevention measures are generally followed, outbreaks still can occur when animals are colonized with STEC O157.

During 1991--2005, CDC received reports of 32 outbreaks of E. coli O157 that were associated with animals in public settings (6). Among these, venues in certain outbreaks (5,7,8) were not in compliance with NASPHV guidelines (1), with reported inadequate handwashing facilities, permitted consumption of food or drink in animal areas, unsupervised handwashing, and no signage. During 2006--2008, five E. coli O157 outbreaks related to animal settings were reported (CDC, unpublished data, 2009).

NASPHV guidelines include recommendations on handwashing, venue design, animal care and management, risk communication, and oversight needed for animals in public settings. Day camp leaders were not completely knowledgeable of NASPHV guidelines before this outbreak but demonstrated familiarity with certain recommendations for reducing human illness in animal settings. NASPHV recommendations should become well known to petting zoo operators and the agencies that provide regulatory oversight over these animal venues.

Acknowledgments

This report is based, in part, on contributions by C Minor, Florida Dept of Health; T Holt, DVM, W Jeter, DVM, J Crews, DVM, and J Carter, Florida Dept of Agriculture and Consumer Svcs.

References

1. CDC. Compendium of measures to prevent disease associated with animals in public settings, 2007: National Association of State Public Health Veterinarians, Inc. (NASPHV). MMWR 2007;56(No. RR-5).
2. Mead PS, Slutsker L, Dietz V, et al. Food-related illness and death in the United States. Emerg Infect Dis 1999;5:607--25.
3. Su C, Brandt LJ. Escherichia coli O157:H7 infection in humans. Ann Intern Med 1995;123:698--714.
4. Keen JE, Elder RO. Isolation of Shiga-toxigenic Escherichia coli O157 from the surfaces and the oral cavity of finished beef feedlot cattle. J Am Vet Med Assoc 2002;220:756--63.
5. CDC. Outbreaks of Escherichia coli O157:H7 associated with petting zoos---North Carolina, Florida, and Arizona, 2004 and 2005. MMWR 2005;54:1277--80.
6. Steinmuller N, Demma L, Bender JB, Eidson M, Angulo FJ. Outbreaks of enteric disease associated with animal contact: not just a foodborne problem anymore. Clin Infect Dis 2006;43:1596--602.
7. CDC. Outbreaks of Escherichia coli O157:H7 infections among children associated with farm visits---Pennsylvania and Washington, 2000. MMWR 2001;50:293--7.
8. Crump JA, Sulka AC, Langer AJ, et al. An outbreak of Escherichia coli O157:H7 infections among visitors to a dairy farm. N Engl J Med 2002;347:555--60.

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Date last reviewed: 4/30/2009