大分市およびその近郊における犬糸状虫伝搬に関する蚊およびブユの自然感染調査

抄録

Investigations on mosquitoes and blackflies to determine a vector of Dirofilaria immitis in residential areas were carried out at 1 site in Oita City and at 3 sites in Hasama Town, Oita Prefecture, from May to December in 1994 and from June to December in 1995. Wild female mosquitoes were collected at night by a light trap, and in the evening by a hand net while being attracted to a collector, or CO_2 gas from dry ice. Among 8 mosquito species collected, Aedes albopictus and Culex tritaeniorhynchus were the most abundant species as a daytime and a nighttime biter, respectively. In all catches, 1 out of 1,009 Ae. albopictus and 2 out of 561 Cx. tritaeniorhynchus were naturally infected with third-stage larva(e) of D. immitis. The female mosquitoes with third-stage larva(e) were found from July to September. Adult blackflies (322 females, 7 species) collected by a hand net were all negative with larvae of D. immitis. Considering their anthropophily as well as zoophily, it is concluded that one or both of Ae. albopictus and Cx. tritaeniorhynchus play(s) a major role in the transmission of D. immitis among dogs, and also possibly from dogs to humans in the three residential areas studied, and that transmission to humans may occur only during the summer months.