1. Division of Community Health, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland, Canada, A1B 3V6
2. Department of Population Medicine, University of Guelph, 50 Stone Road East, Guelph, Ontario, Canada, N1G 2W1
3. Foodborne, Waterborne and Zoonotic Infections Division, Public Health Agency of Canada, 160 Research Lane, Suite 206, Guelph, Ontario, Canada, N1G 5B2