1. Colorado State University, College of Veterinary Medicine and Biomedical Sciences, 300 West Drake Ave., Fort Collins, Colorado 80523, USA
2. Rickettsial Zoonoses Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
3. Rickettsial Zoonoses Branch, Centers for Disease Control and Prevention, National Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, Washington, USA