Abstract
1 Laboratorium voor Microbiologie University of Ghent, B-9000 Ghent, Belgium
2 Provinciaal Verbond voor Dierenziektenbestrijding, Torhout, Belgium
3 Department of Laboratory Medicine SB-10, University of Washington Medical Center, Seattle, Washington 98195
4 Institute for Hygiene and Laboratory Medicine, Städtische Krankenanstalten Krefeld, Germany
5 and Queensland Department of Primary Industries, Animal Research Institute, Yeerongpilly, Queensland 4105, Australia