1. Blood Systems Research Institute, 270 Masonic Avenue, San Francisco, California 94118, USA
2. Department of Laboratory Medicine, University of California at San Francisco, 521 Parnassus Avenue, San Francisco, California 94143, USA
3. Current address: NCIRD, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, Georgia 30333, USA
4. Marine Wildlife Veterinary Care and Research Center, California Department of Fish and Wildlife, 1451 Shaffer Road, Santa Cruz, California 95060, USA
5. Veterinary Medical Teaching Hospital, University of California at Davis, One Shields Avenue, Davis, California 95616, USA
6. Athens Veterinary Diagnostic Laboratory, College of Veterinary Medicine, University of Georgia, 501 D. W. Brooks Drive, Athens, Georgia 30602, USA