Marc J M Bonten1, Dik Mevius2. 1. Department of Medical Microbiology, Julius Center for Health Sciences and Primary Care University Medical Center Utrecht. 2. Department of Bacteriology and Transmissible Spongioform Encephalitis, Central Veterinary Institute of Wageningen University and Research Centre, Lelystad Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, The Netherlands.