1. Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden.
2. Department of Disease Control and Epidemiology, National Veterinary Institute, Uppsala, Sweden.
3. Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Skara, Sweden.
4. Moredun Research Institute, Pentlands Science Park, Penicuik, Scotland, United Kingdom.
5. Department of Virology, Immunobiology, and Parasitology, National Veterinary Institute, Uppsala, Sweden.