1. Institute for Microbiology, University of Veterinary Medicine, Foundation; Hannover Germany
2. Institute of Veterinary Pathology, Centre for Clinical Veterinary Medicine, Ludwig-Maximilians-University Munich; Munich Germany
3. Department of Veterinary Diagnostic and Production Animal Medicine; College of Veterinary Medicine, Iowa State University; Ames USA
4. Clinic for Swine, Centre for Clinical Veterinary Medicine, Ludwig-Maximilians-University Munich; Oberschleissheim Germany