Virological and Epidemiological Studies on Encephalitis in Chiang Mai Area, Thailand, in the Year of 1982 VII. Mosquitocollectionand virus isolation

Totalling 15513 mosquitoes composed of Culex tritaeniorhynchus, Cx. gelidus and Cx. fuscocephala were collected in Chiang Mai Area from July 13 to August 12, 1982, and processed for virus isolation, using Aedes albopictus, clone C6/36, cells. JE virus was not isolated, although two unidentified flavivirus and 59 strains of unknown filtrable agents producing cytopathic changes in C6/36 cells were detected. Host prefere- nce of the above three species of Culex mosquitoes showed that they fed mostly on swine, followed by smaller percentages of bovines. Daily survival rate observed for Cx. tritae- niorhynchus females in Chiang Mai did not differ significantly from those observed in