1. Department of Bacteriology and Immunology, , Bedrijvenlaan 7, 2800, Mechelen, Belgium
2. Intervet Belgium, Bedrijvenlaan 7, 2800, Mechelen, Belgium
3. Co-ordination Centre for Veterinary Diagnostics, Groeselenberg, 99,1180, Brussels, Belgium
4. Department of Small Stock Diseases, Veterinary and Agrochemical Research Centre, Groeselenberg, 99, 1180, Brussels, Belgium
5. Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, , Salisburylaan 133, 9820, Merelbeke, Belgium