1. National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
2. Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States
3. Statens Serum Institut, Unit of Gastrointestinal Infections, Copenhagen, Denmark
4. Association of Public Health Laboratories, Silver Spring, Maryland, United States
5. Members of the working group are listed at the end of the article