1. Department of Medical Microbiology; Albert Schweitzer Hospital; Dordrecht The Netherlands
2. Laboratory of Medical Microbiology and Immunology; St. Elisabeth Hospital; Tilburg The Netherlands
3. Division Environmental Epidemiology; Institute for Risk Assessment Sciences; Utrecht University; Utrecht The Netherlands
4. Department of Medical Microbiology; University Medical Center Groningen; University of Groningen; Groningen The Netherlands
5. Department of Virology; Erasmus Medical Centre; Rotterdam The Netherlands
6. National Institute of Public Health and the Environment; Centre for Infectious Disease Control; Bilthoven The Netherlands