1. Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado.
2. Special Pathogens Branch, Division of Viral and Rickettsial Diseases, National Center for Zoonotic, Vector-Borne, and Enteric Diseases, Coordinating Center for Infectious Diseases, U.S. Centers for Disease Control and Prevention, Atlanta, Georgia.