1. Enteric Diseases Laboratory Branch, Division of Foodborne, Waterborne and Environmental Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
2. Alaska State Public Health Laboratories, Division of Public Health, Alaska Department of Health and Social Services, Anchorage, Alaska, USA
3. Epidemic Intelligence Service Assigned to the State of Alaska Section of Epidemiology, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
4. Division of Foodborne, Waterborne and Environmental Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA