1. Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 268, CH-8057 Zurich, Switzerland
2. Institute of Social and Preventive Medicine, University of Bern, Mittelstrasse 43, CH-3012 Bern, Switzerland
3. Cantonal Hospital Winterthur, Brauerstrasse 15, CH-8400 Winterthur, Switzerland