1. Quantitative
Veterinary Epidemiology Group, Wageningen Institute of Animal Sciences
(WIAS), Wageningen University, P.O. Box 338, 6700 AH Wageningen, The Netherlands
2. Centre
for Zoonoses and Environmental Microbiology, Centre for Infectious
Disease Control (CIb), National Institute for Public Health and the Environment (RIVM), P.O. Box 1, 3720 BA Bilthoven, The Netherlands
3. Department
of Medical Microbiology and Infection Control, VU University Medical Center, P.O. Box
7057, 1007 MB Amsterdam, The Netherlands
4. Faculty
of Veterinary Medicine, Institute for Risk Assessment Sciences (IRAS), Utrecht University, P.O.
Box 80178, 3508 TD Utrecht, The Netherlands