1. Wildlife/Livestock Disease Investigations Team, Western Region, Veterinary Services, Animal and Plant Health Inspection Service, US Department of Agriculture, Fort Collins, Colorado 80521, USA
2. Animal Population Health Institute, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado 80523, USA
3. Current address: North Slope Borough Public Health Office, 5000 Boxer Street, Barrow, Alaska 99723, USA
4. National Veterinary Services Laboratory, Veterinary Services, Animal and Plant Health Inspection Service, US Department of Agriculture, Ames, Iowa 50010, USA
5. Rocky Mountain Regional Animal Health Laboratory, Denver, Colorado 80211, USA
6. Department of Environmental and Radiological Health Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado 80523, USA
7. Professor emeritus, Colorado State University, 1678 Campus Delivery, Fort Collins, Colorado 80521, USA