1. Department of Veterinary Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California 95616, USA
2. Department of Fish and Game, Wildlife Investigations Laboratory, 1701 Nimbus Road, Suite D, Rancho Cordova, California 95670, USA
3. Department of Epidemiology and Preventive Medicine, School of Veterinary Medicine, University of California, Davis, California 95616, USA