Agricultural Fair, Ontario, Canada

Warshawsky et al (2002) investigated an outbreak of E. coli O157:H7 associated with a large agricultural fair conducted between September 10 and 19, 1999, in Ontario, Canada. This study indicated that 7 cases of E. coli O157:H7 infections were associated with animal contact at the agricultural pavilion of the regional fair. Sub-typing revealed that five of the seven cases were extremely uncommon E. coli O157:H7 PT 27 while the remaining two were common E. coli O157:H7 PT 14.  The E. coli O157:H7 PT 27 pattern matched with three samples from goats and one sample from sheep from the traveling petting zoo. The researchers further noted that the clustering of positive cases on the two weekends of the fair indicated that exposures could be a result of difficulty in manure disposal and environmental cleaning due to high volumes of visitors.  The results from this case control study strongly suggested that the goats and sheep from the petting zoo were the source of the E. coli O157:H7. The detailed history from two primary sources indicated that the rails and the environment surrounding the petting zoo could also have been contaminated and could have acted as a source of transmission. The researchers recommended that standards should be outlined for adequate hand washing facilities, appropriate disposal of manure, proper cleaning environment surrounding the petting zoos, including the rails and floors.