1. Vector-Borne Diseases Division, Bureau of Laboratories, Center for Disease Control, Public Health Service, Fort Collins, Colorado 80521
2. Tropical Diseases Laboratory, Bureau of Laboratories, Center for Disease Control, Public Health Service, San Juan, Puerto Rico 00936
3. Division of Mammals, National Museum of Natural History, Smithsonian Institute, Washington, D.C. 20560
4. Virology Division, Bureau of Laboratories, Center for Disease Control, Atlanta, Georgia 30333