Isolation of Western Equine Encephalomyelitis (Wee) Virus From Mosquitoes In Saskatchewan, 1962

Saskatchewan, in the summer of 1962, was the scene of an extensive outbreak of western equine encephalomyelitis (WEE) in horses. The results of mosquito survey work showed Culiseta inornata and Culex tarsalis respectively to be the two most abundant mosquito species during midsummer. These species are those reported to be most commonly associated with outbreaks of WEE. Five hundred and sixty-four pools of mosquitoes were examined for the presence of WEE virus. Six pools, three of C. tarsalis and one each of C. inornata, Aedes flavescens and Aedes dorsalis, yielded WEE virus. Positive mosquitoes were from St. Walburg (C. inornata), Saskatoon (C. tarsalis - two, A. dorsalis - one), Outlook (C. tarsalis) and Kisbey (A. flavescens).