A virus of the California encephalitis complex was isolated from two pools of the mosquito Culiseta inornata, collected in mammalian burrows of Alberta during the summer of 1965. This is the first recorded isolation of California encephalitis virus from mosquitoes in Canada.

Mosquitoes were collected in Alberta during the spring, summer, and early fall of 1965. Western encephalitis (WE) virus was isolated from pools collected between August 11 and August 25.Two positive pools, one of Aedes vexans (Meigen) and one of Culiseta inornata (Williston) were collected by sweep nets in irrigated areas of southern Alberta near places where horses were reported sick with WE virus. Seven other positive pools, three of C. inornata and four of Culex tarsalis Coquillett, were collected in southern Alberta from mammalian burrows, which are hibernating habitats for C. inornata, C. tarsalis, and Anopheles earlei Vargas. This indicates that C. tarsalis and C. inornata can enter hibernation infected with WE virus. None of the A. earlei pools tested were positive for WE virus.About 50% of the C. inornata and 9% of the C. tarsalis collected from mammalian burrows were blood-engorged at the time of collection. None of the A. earlei collected from mammalian burrows were blood-fed.

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Collection on a filter membrane as a routine culture method has proved of great advantage in the isolation of Mycobacterium tuberculosis from the cerebrospinal fluid. Its use, during combined intrathecal treatment with streptomycin and Purified Protein Derivative of tuberculin, shows that the organisms persist for an unexpectedly long time in the cerebrospinal fluid. In some instances, focal reaction to P.P.D. seems to liberate tubercle bacilli from the lesions into the fluid. Direct culture of C.S.F. on Loewenstein medium gave less than two positive specimens per patient and no positive cultures later than the second week of treatment. Filtration gave more profuse growth and persistence of positive cultures during treatment for as long as 28 weeks in some cases.

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