1. Veterinary Epidemiology Unit, Department of Obstetrics, Reproduction, and Herd Health, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
2. Operational Directorate Public Health and Surveillance, Scientific Institute of Public Health, Brussels, Belgium.
3. Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
4. Technology and Food Science Unit, Institute for Agricultural and Fisheries Research, Melle, Belgium.
5. Department of Bacteriology and Immunology, CODA-CERVA-VAR, Brussels, Belgium.