[Surveillance of Japanese Encephalitis Vector Mosquitoes in the Republic of Korea in 2024]

Japanese encephalitis (JE) is a mosquito-borne disease endemic to Asia and the Western Pacific, including Republic of Korea (ROK), and is primarily transmitted by Culex tritaeniorhynchus. The Korea Disease Control and Prevention Agency conducts annual surveillance of mosquito vectors. This study assessed the status of JE vectors in 2024 and analyzed trends in their density in relation to climatic factors.

Surveillance was conducted at 62 locations through cooperation with the Regional Centers for Disease Control, the Ministry of National Defense, Institute of Health and Environment in local government, and the Regional Centers for Vector Surveillance against Climate Change. Black light traps were used to collect mosquitoes twice a week, primarily in livestock sheds. A comparative analysis was performed using data from ten long-term surveillance sites. Meteorological data, including temperature and rainfall, were obtained from the Korea Meteorological Administration's open data portal to evaluate their effects on mosquito occurrence.

Seven genera and eighteen mosquito species were identified in 2024, with an overall Trap Index (TI) of 266.5. The TI for Cx. tritaeniorhynchus was 89.8, indicating a 34.8% increase compared with that in 2023.

Climate change has likely contributed to the JE vector population. In 2024, the population of JE vectors increased, likely due to rising average temperatures and reduced rainfall. The density of Cx. tritaeniorhynchus in ROK has been increasing annually. Therefore, since vector density is closely related to patient management and disease prevention, continuous monitoring and control are necessary.