1. Robert Koch Institute, Berlin, Germany
2. Institute of Public Health, Muenster, North-Rhine Westphalia, Germany
3. Regional Health Authority, Hanover, Lower Saxony, Germany
4. Government Health Service Institute, Dillenburg, Hesse, Germany
5. Bavarian Health and Food Safety Authority, Munich, Bavaria, Germany
6. Institute for Hygiene and Infection Control, Landau, Rhineland-Palatinate, Germany
7. Thuringian State Authority for Food Safety and Consumer Protection, Erfurt, Thuringia, Germany
8. State Health Office, Stuttgart, Baden-Wuerttemberg, Germany