At least 11 children and two adults who visited the petting barn during Vancouver's Pacific National Exhibition developed an infection caused by E. coli O157:H7. The ill lived throughout British Columbia and ranged in age from 21 months to 69 years. Petting zoos have been associated with previous outbreaks of E. coli. The Pacific National Exhibition had all of the proper precautions in place, including well stocked handwashing stations. The fair ran for 17 days and ended on the Canadian Labor Day, September 7. More than 855,000 people attended. As of September 16, public health investigators had not determined the specific cause of the outbreak.