CALIFORNIA ENCEPHALITIS AND POWASSAN VIRUS ACTIVITY IN BRITISH COLUMBIA, 196912

Abstract

McLean, D. M. (Dept. Microbiology, Univ. of British Columbia, Vancouver 8, B.C., Canada), M. A. Crawford, S. R. Ladyman, R. R. Peers and K. W. Purvin-Good. California encephalitis and Powassan virus activity in British Columbia, 1969. Amer. J. Epid., 1970, 92: 266–272.—A strain of California encephalitis virus was isolated from a mixed mosquito pool comprising Aedes vexans and A. canodentis which was collected near Penticton, B.C, Canada in 1969. Virus isolation from vector mosquitoes provides the first definite evidence that mosquito-borne California encephalitis virus is endemic in British Columbia. Hemagglutinin inhibiting antibodies to Powassan and/or St. Louis encephalitis viruses were detected in sera from 133 of 833 rodents captured between April and August, 1969, and 43 sera neutralized one or both of these viruses. Sera from 94 of 422 Marmota fla-viventris inhibited group B hemagglutinin including 41 which inhibited Powassan virus exclusively. Serologic results strongly suggest the prevalence of tick-borne Powassan virus and possibly other group B arboviruses, in British Columbia.