1. Department for Infectious Disease Epidemiology, Robert Koch Institute, Berlin, Germany.
2. Public Health Office, Ploen, Germany.
3. National Reference Center for Salmonella and Other Bacterial Enteric Pathogens, Robert Koch Institute, Wernigerode, Germany.
4. Federal Research Institute of Nutrition and Food, Max Rubner Institute, Karlsruhe, Germany.
5. Baden-Württemberg State Health Office, Department of Epidemiology and Health Reporting, Stuttgart, Germany.
6. Consumer Protection Office, Halle, Germany.
7. Federal Institute for Risk Assessment, Berlin, Germany.
8. Reference Laboratory for Listeriosis (until 2009), University of Heidelberg, Heidelberg, Germany.