Foodborne Botulism in Canada, 1985–2005

Daniel Leclair, Joe Fung, Judith L. Isaac-Renton, Jean-Francois Proulx, Jennifer May-Hadford, Andrea Ellis, Edie Ashton, Sadjia Bekal, Jeffrey M. Farber, Burke Blanchfield, and John W. Austin

Author affiliations: Health Canada, Ottawa, Ontario, Canada (D. Leclair, J.W. Austin, J.M. Farber, B. Blanchfield); British Columbia Provincial Health Services Authority, Vancouver, British Columbia, Canada (J.L. Isaac-Renton, J. Fung); Nunavik Regional Board of Health and Social Services, Kuujjuaq, Quebec, Canada (J.-F. Proulx); Public Health Agency of Canada, Guelph, Ontario (J. May-Hadford); Laboratoire de santé publique du Québec, Sainte-Anne-de-Bellevue, Quebec, Canada (S. Bekal); ProvLab, Edmonton, Alberta, Canada (E. Ashton); Canadian Food Inspection Agency, Ottawa (A. Ellis)

Suggested citation for this article
During 1985–2005, a total of 91 laboratory-confirmed outbreaks of foodborne botulism occurred in Canada; these outbreaks involved 205 cases and 11 deaths. Of the outbreaks, 75 (86.2%) were caused by Clostridium botulinum type E, followed by types A (7, 8.1%) and B (5, 5.7%). Approximately 85% of the outbreaks occurred in Alaska Native communities, particularly the Inuit of Nunavik in northern Quebec and the First Nations population of the Pacific coast of British Columbia. These populations were predominantly exposed to type E botulinum toxin through the consumption of traditionally prepared marine mammal and fish products. Two botulism outbreaks were attributed to commercial ready-to-eat meat products and 3 to foods served in restaurants; several cases were attributed to non-Native home-prepared foods. Three affected pregnant women delivered healthy infants. Improvements in botulism case identification and early treatment have resulted in a reduction in the case-fatality rate in Canada.
Foodborne botulism, a notifiable disease in Canada, results from the ingestion of foods contaminated with preformed botulinum neurotoxin types A, B, E, or F, produced by Clostridium botulinum groups I and II (1). More rarely, outbreaks of foodborne botulism in the United States, India, and China have been caused by neurotoxigenic C. butyricum type E (2,3) and C. baratii type F (4). In Canada, C. botulinum type E has been the most common serotype since the first type E outbreak in 1944 in Nanaimo, British Columbia (reported in 1947) (5–7).
Six forms of botulism have been described in the literature (8), but only foodborne and infant botulism and rare cases of adult colonization have been reported in Canada (1,9). Regardless of the form or serotypes involved, however, human botulism is a medical emergency that requires rapid intervention. Because prompt administration of antitoxin can reduce the severity of the disease (10), the decision for treatment is based on clinical diagnosis and epidemiologic information, without laboratory confirmation.
Investigation of foodborne botulism incidents provides useful information regarding implicated foods and conditions resulting in toxin formation. The last epidemiologic review on foodborne botulism in Canada was done for the 1971–1984 period (7). Since then, annual summaries of botulism cases were inconsistently published through disease surveillance reports (e.g., 11,12). Here, we summarize reports of all laboratory-confirmed cases of foodborne botulism in Canada during 1985–2005.