1. Centers for Disease Control and Prevention, National Center for Infectious Diseases, Division of Viral and Rickettsial Diseases, Atlanta, Georgia.
2. Indian Health Service, Whiteriver Service Unit, Whiteriver, Arizona.
3. Indian Health Service, San Carlos Service Unit, San Carlos, Arizona.
4. Arizona Department of Health Services, Vector Borne Disease Unit, Phoenix, Arizona.
5. Indian Health Service, Division of Epidemiology, Albequerque, New Mexico.