1. Wildlife Health Center, School of Veterinary Medicine, University of California, Davis, California 95616, USA
2. The Marine Mammal Center, Golden Gate National Recreation Area, Sausalito, California 94965, USA
3. Department of Pathology, Microbiology and Immunology, University of California, Davis, California 95616, USA
4. California Animal Health and Food Safety Laboratory, University of California, Davis, California 95616, USA