1. Department of Pathology; Faculty of Veterinary Medicine; University of Liege; Sart Tilman B-43 B-4000 Liege Belgium
2. Department of Large Animal Medicine and Reproduction; Faculty of Veterinary Medicine; University of Lidge; Sart Tilman B-42 B-4000 Likge Belgium
3. National Centre for Disease Investigation; MAF Operations; PO Box 40742 Upper Hutt New Zealand