Enteric illness in Ontario, Canada, from 1997 to 2001

Enteric illness is a common problem worldwide. In Ontario (population of 11.4 million, 2001 Census of Canada), laboratory-confirmed cases of "reportable" enteric diseases are reported to local health units. Public health staff members investigate these illnesses and subsequently report details to the Ministry of Health and Long-Term Care through an electronic reporting system. From 1997 to 2001, 44,451 sporadic cases of illness attributable to eight enteric pathogens (Campylobacter, Salmonella, verotoxin-producing Escherichia coli, Yersinia, Shigella, hepatitis A, Listeria, and Clostridium botulinum) were reported. This number was less than the 56,690 cases reported from 1992 to 1996. Campylobacter accounted for the highest annual average incidence rate at 42.3 cases per 100,000 persons, with Salmonella following at 22.6, verotoxin-producing E. coli at 3.7, Yersinia at 3.0, Shigella at 2.7, hepatitis A at 2.3, and Listeria at 0.3. The 4 months from June to September accounted for almost half (46.5%) of all cases. For 74.0% of the outbreaks associated with these eight enteric pathogens, foodborne contamination was identified as the mode of transmission. Poultry and other meat items accounted for 68.4% of the food items when food was identified as the vehicle. Admittedly, the "foods" and "modes of transmission" identified may have been subject to investigator bias based on previous knowledge. The most common risk setting, which was reported in approximately half of the cases, was private homes; travel-associated illness and restaurants were the second and third most frequently reported risk settings at 24.6 and 14.1%, respectively. Findings from this study suggest that public health efforts should be directed toward safe food handling in the home during the summer months.