Mosquito Surveillance and Detection of Japanese Encephalitis Virus at Two Points of Entry (PoE), Incheon International Airport and Incheon Port, in the Republic of Korea, 2023

Monitoring invasive mosquitoes and selected pathogens was conducted biweekly at ports of entry (POEs), the Incheon Port (IP), and Incheon International Airport (IA), from June to October 2023. A total of 618 mosquitoes representing 2 subfamilies, 6 genera, and 13 species were collected. At IP-Garo Park (IP-GP), a small park, and IP-Gate3 (IP-G3), a facility staffed 24 h a day and equipped with a septic tank, the incidence of Aedes albopictus and Culex pipiens s.l. was the highest, respectively.

A total of 115 pools of female mosquitoes were tested for flaviviruses using qRT-PCR. Japanese encephalitis virus (JEV) was detected in 1pool of Cx. pipiens s.l. which were collected at IP during September 4, 2023. Maximum likelihood estimation (MLE) value for Cx. pipiens collected from June to October was 0.092. The nonstructural protein 5 (NS 5)/3′-untranslated region (UTR) of the JEV genome was sequenced. Sequence alignment of the complete NS 5 gene showed high amino acid similarity (98.67%) to JF915894, characterized as genotype V (G-5) from China. These results were shared with the local public health center where the JEV infected mosquitoes were collected to develop control measures for infectious diseases in vector mosquito populations.

The estimated JEV infection rate (MLE value: < 1) and phylogenetic data demonstrate the inflow of JEV G-5 in Cx. pipiens at IP of entry and stress the importance of surveillance for vector mosquitoes at POE.