Isolation of a virus closely related to Powassan virus from Dermacentor andersoni collected along North Cache la Poudre River, Colo.

ConclusionsA virus closely related, if not identical, to Powassan virus has been isolated from Dermacentor andersoni from northern Colorado. A nonreciprocal relationship between RSSE virus and 791A-52 virus is indicated by the cross neutralization tests. The importance of Dermacentor andersoni in maintenance of this virus is unknown. Although thousands of this tick species collected in many areas in the western United States have been examined for viruses in this laboratory, this is the only isolation of this agent. Since these prior studies of ticks at the Rocky Mountain Laboratory were directed specifically toward study of the ecology of Coloradotick fever virus, the ecology of the 791A-52 virus is unknown. Field and laboratory studies on this subject are in progress.