1. a Department of Small Stock Diseases , Veterinary and Agrochemical Research Centre (VAR) , Groeselenberg 99, 1180, Brussel, Belgium
2. b Intervet Belgium , Bedrijvenlaan 7, 2800, Mechelen, Belgium
3. c Co-ordination Centre for Veterinary Diagnostics VAR , Groeselenberg 99, 1180, Brussel, Belgium
4. d Department of Pathology, Bacteriology and Avian Diseases , Faculty of Veterinary Medicine , Salisburylaan 133, 9820, Merelbeke, Belgium