Nationwide Japanese encephalitis alert issued after virus found in mosquitoes
Health authorities encouraged Koreans, long-term visitors and travelers to high-risk countries to follow bite-prevention guidelines and consider vaccination.
Public health center employees conduct mosquito control activities at Suwon Stream in Suwon, Gyeonggi, on July 31, 2024.YONHAP
A nationwide Japanese encephalitis alert has been issued on Wednesday after the virus was detected in a mosquito found in Daegu.
A Japanese encephalitis alert is issued by the Korea Disease Control and Prevention Agency (KDCA) when more than 500 culex tritaeniorhynchus mosquitoes — a mosquito species that can transmit the disease — are caught per day on average during operations conducted twice a week, or when the virus is detected in vector species.
The KDCA previously issued an advisory on March 20 after finding culex tritaeniorhynchus for the first time this year.
This year's advisory came earlier than usual, with last year's having been issued on Aug. 1, 2025.
However, the agency said a direct comparison is difficult because last year's alert was triggered by rising mosquito density while this year's followed the detection of the virus. The virus was found in culex pipiens, which is a mosquito species commonly found in environments rich in organic matter such as septic tanks and stagnant water.
The KDCA operates a program monitoring Japanese encephalitis vectors at 14 sites nationwide. The agency has recently added culex pipiens to the list of species it monitors.
Korea reports around 17 Japanese encephalitis cases each year. The first case is typically reported in August or September, with infections continuing through November.
Of the total 79 cases reported over the past five years, 60.8 percent were found in males. By age group, those aged 60 and older accounted for 65.9 percent of all cases.
Japanese encephalitis initially causes relatively mild symptoms such as fever, headache and vomiting. However, some infections progress to encephalitis, resulting in severe symptoms including high fever, seizures, impaired consciousness, paralysis and disorientation.
Public health center employees conduct mosquito control activities at a neighbourhood in Dong District, Daegu, on Aug. 17, 2022.NEWS1
Among patients whose condition progresses to encephalitis, 20 percent to 30 percent may die. Of those who survive, 30 percent to 50 percent may be left with neurological complications.
The KDCA stressed that vaccination is the most effective way to prevent infection.
Children born in 2013 or later are eligible to be vaccinated through the national immunization program. Adults without a vaccination history who live in high-risk areas such as near rice paddies or livestock facilities, travelers to countries at risk of Japanese encephalitis and foreign nationals staying in Korea for extended periods are also advised to consider vaccination.
The agency also urged people to follow mosquito-bite prevention guidelines, including wearing long sleeves and pants during outdoor activities and using insect repellent.
"Local governments should strengthen larval control efforts in areas with stagnant water in urban settings and carry out mosquito control in basements, wooded areas and other mosquito habitats," KDCA Commissioner Lim Seung-kwan said. "We must minimize the number of cases through vaccination and mosquito-control measures."
This article was originally written in Korean and translated by a bilingual reporter with the help of generative AI tools. It was then edited by a native English-speaking editor. All AI-assisted translations are reviewed and refined by our newsroom.
