Japanese Encephalitis Virus in Culicine Mosquitoes (Diptera: Culicidae) of the Republic of Korea, 2008-2010

A total of 150,805 culicine female mosquitoes were captured by Mosquito Magnet, black light, and New Jersey light traps, and at resting collections in the Republic of Korea from 2008 to 2010 as part of the U. S. Forces Korea malaria and Japanese surveillance programs. Mosquitoes were identified and culicine mosquitoes placed in pools of up to 30 mosquitoes each, by species and date of collection, and screened for flaviviruses using a reverse transcription-polymerase chain reaction assay. A total of 98/6,845 (1.4%) pools were positive by reverse transcription-polymerase chain reaction for Japanese encephalitis virus (JEV). A total of 92/2,031 (4.5%) pools of Culex tritaeniorhynchus were positive for JEV and accounted for 93.9% (92/98) of all JEV positive pools. A total of 4/804 (0.5%) and 2/175 (1.1%) pools of C. pipiens and C. bitaeniorhynchus, respectively, were positive for JEV. The JEV maximum likelihood estimations (estimated number of viral RNA positive mosquitoes per 1,000) for C. tritaeniorhynchus, C. bitaeniorhynchus, and C. pipiens were 1.71, 1.02, and 0.36 respectively. JEV is a severe health threat for local populations and of significant concern for nonimmune (unvaccinated) U.S. soldiers, civilians, and family members deployed to the Republic of Korea.