1. Centre for Fish and Wildlife Health, Vetsuisse Faculty, University of Bern, Bern, Switzerland
2. Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
3. Current address: Centre for Laboratory Medicine, Division of Veterinary Diagnostics, St-Gallen, Switzerland
4. National Centre for Enteropathogenic Bacteria and Listeria, Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Switzerland
5. Swiss Ornithological Institute, Sempach, Switzerland