1. Institute for Clinical Medicine, University of Oslo, Oslo, Norway;
2. Department of Otolaryngology, Head and Neck Surgery, Oslo University Hospital, Oslo, Norway;
3. Department of Analysis and Diagnostic, Norwegian Veterinary Institute, Oslo, Norway;
4. Department of Animal Health and Food Safety, Norwegian Veterinary Institute, Oslo, Norway;
5. Department of Otolaryngology, Head and Neck Surgery, Akershus University Hospital, Akershus and Oslo, Norway;
6. Center for Clinical Research, Uppsala University, Västerås, Sweden