1. Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, California 95616, USA
2. Pathology Department, The Zoological Society of San Diego, P.O. Box 551, San Diego, California 92112-0551, USA
3. Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California 95616, USA
4. Califomia Veterinary Diagnosis Laboratory System, School of Veterinary Medicine, University of California, Davis, California 95616, USA
5. California Department of Fish and Game, Wildlife Investigation Laboratory, 1701 Nimbus Road, Suite D, Rancho Cordova, California 95670, USA
6. Division of Environmental Studies, University of California, Davis, California 85616, USA