1. California Veterinary Diagnostic Laboratory System, University of California, School of Veterinary Medicine, Davis, CA 95616
2. Zoonotic Diseases Laboratory, Livestock and Poultry Sciences Institute, Agricultural Research Service, US Department of Agriculture, BARC-East, Beltsville, MD 20705
3. Department of Veterinary Microbiology and Immunology, University of California, School of Veterinary Medicine, Davis, CA 95616