- Ad P Koets: Department of Bacteriology and TSE, Central Veterinary Institute, part of Wageningen University and Research Centre, Edelhertweg 15, 8219 PH, Lelystad, The Netherlands. ad.koets@wur.nl.
- Yrjö T Gröhn: Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA. ytg1@cornell.edu.