1. U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services, National Veterinary Services Laboratories, P.O. Box 844, Ames, Iowa 50010, USA
2. Montana Department of Fish, Wildlife and Parks, Research and Technical Services Bureau, Fish, Wildlife and Parks Building, Montana State University Campus, Bozeman, Montana 59715, USA
3. U.S. Department of Agriculture, Animal and Plant Health Inspection Services, Veterinary Services, 2206 Green Valley Drive, Billings, Montana 59102, USA
4. Montana Department of Livestock, Veterinary Diagnostic Laboratory, P.O. Box 997, Bozeman, Montana 59771, USA