Vector Competence of Japanese Mosquitoes for Dengue and West Nile Viruses

摘要

23.1 Introduction Dengue virus (DEV) and West Nile virus (WNV) belong to the genus Flavivirus (family Flaviviridae). Dengue virus replicates in humans as the primary vertebrate host and Aedes (Stegomyia) aegypti and Ae. (Stg.) albopictus mosquitoes as the vectors. In contrast, WNV replicates in birds as the reservoir host, while incidental infection occurs in humans and horses. Although dengue is not endemic in Japan, nor is there a stable population of Ae. aegypti, epidemics broke out in a port town of Nagasaki in 1942. About 200,000 typical clinical cases were recorded. Several Ae. (Stg.) mosquito species, including Ae. albopictus, are widely distributed in Japan. Furthermore, imported cases of the patients are increasing. On the other hand, an imported case of a West Nile fever patient was reported in 2005. Possible vector information of WNV is lacking in Japan. For these reasons, we investigated the possible vector competence of Japanese mosquitoes to DEV and WNV.