1. Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, Canada.
2. National Microbiology Laboratory Branch, Public Health Agency of Canada, Guelph, Canada.
3. National Microbiology Laboratory Branch, Public Health Agency of Canada, St. Hyacinthe, Canada.
4. Health Promotion and Chronic Disease Prevention Branch, Public Health Agency of Canada, Ottawa, Canada.
5. Sunnybrook Research Institute, Toronto, Canada.
6. Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada.