Foodborne Botulism in Canada, 1985–2005

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.