Japanese Encephalitis Virus Found in Urban Mosquitoes Triggers Nationwide Alert in South Korea
Nikhil Prasad Fact checked by:Thailand Medical News Team Jun 18, 2026 1 hour, 7 minutes ago
Medical News: South Korean health authorities have issued a nationwide Japanese Encephalitis (JE) alert after detecting Japanese Encephalitis virus genes in urban mosquitoes collected in the city of Daegu. The development has raised fresh concerns among public health experts because the virus was identified in a mosquito species commonly found in densely populated urban environments, potentially expanding the scope of exposure risks beyond traditional rural settings.
Japanese Encephalitis virus detected in urban mosquitoes prompts South Korea to issue a nationwide health alert
Virus Detection Triggers Immediate National Alert
The Korea Disease Control and Prevention Agency (KDCA) announced the alert on June 17 after laboratory testing confirmed the presence of Japanese Encephalitis virus genetic material in mosquitoes captured during routine surveillance operations.
Under national guidelines, a Japanese Encephalitis alert can be issued when virus genes are detected in collected mosquitoes, when mosquito populations reach critical density thresholds, or when a human infection is reported. The latest alert was triggered solely by the discovery of viral genes in mosquito samples from the Daegu region.
South Korea has maintained a mosquito surveillance network since 1975 as part of efforts to prevent outbreaks of mosquito-borne diseases. This year, surveillance activities are being conducted at 14 monitoring locations nationwide from March through October.
Urban Mosquito Species Raises New Concerns
Traditionally, Japanese Encephalitis transmission has been associated with the mosquito species Culex tritaeniorhynchus. However, health authorities have recently expanded surveillance to include Culex pipiens, commonly known as the red house mosquito.
The virus detected in Daegu was found in Culex pipiens, a mosquito species that thrives in urban environments and breeds in stagnant water containing organic material, including septic tanks, drains, puddles, and artificial containers.
Unlike rural mosquito species, red house mosquitoes are well adapted to city environments. They begin appearing in significant numbers from March, increase sharply during late spring and summer, and can remain active until November. The discovery of the virus in this urban mosquito species has heightened concerns that city populations may face greater exposure risks than previously recognized.
Potentially Deadly Neurological Disease
Japanese Encephalitis is a viral infection transmitted through mosquito bites. Most infections are asymptomatic or cause mild symptoms such as fever, headache, nausea, and vomiting.
In rare cases, however, the virus can invade the brain and cause severe encephalitis. Patients may develop high fever, seizures, confusion, paralysis, convulsions, and loss of consciousness. Health authorities warn that between 20 and 30 percent of severe encephalitis cases can be fatal.
Even among survivors, recovery is often incomplete. Studies and surveillance data indicate that 30 to 50 percent of patients recovering
from Japanese Encephalitis-related encephalitis may suffer long-term neurological complications, including cognitive impairment, movement disorders, speech difficulties, behavioral changes, and other permanent disabilities.
Older Adults Account for Most Cases
According to KDCA data, South Korea records an average of approximately 17 Japanese Encephalitis cases each year. The first human cases are usually reported in August or September, with infections continuing through November.
Analysis of 79 reported cases between 2021 and 2025 showed that men accounted for 60.8 percent of infections. Notably, 65.9 percent of all cases occurred in individuals aged over 60 years, highlighting the increased vulnerability of older adults to severe disease.
Vaccination And Mosquito Control Remain Critical
Health officials are urging parents to ensure that children eligible for South Korea’s national immunization program complete their recommended vaccination schedules. Authorities are also advising vaccination for unvaccinated adults living near rice paddies, pig farms, or other high-risk environments, as well as long-term foreign residents and travelers visiting endemic regions across Asia and the Pacific.
Transmission risk of Japanese Encephalitis are typically reported across much of Asia and parts of the western Pacific, including the following countries: Bangladesh, Bhutan, India, Nepal, Pakistan, and Sri Lanka in South Asia; Brunei, Myanmar, Cambodia, Indonesia, Laos, Malaysia, the Philippines, Singapore, Thailand, East Timor (Timor-Leste), and Vietnam in Southeast Asia; China, Japan, North Korea, South Korea, and Taiwan in East Asia; as well as far eastern areas of Russia, northern and eastern parts of Australia, and Papua New Guinea. Risk is generally highest in rural agricultural areas, particularly during or after the rainy season when mosquito populations increase.
This
Medical News report highlights that the discovery of Japanese Encephalitis virus in an urban mosquito species serves as a stark reminder that the disease remains an ongoing public health threat despite the availability of effective vaccines. The finding underscores the need for intensified mosquito control measures, elimination of stagnant water breeding sites, use of repellents and protective clothing, and greater awareness among vulnerable populations. Public health experts stress that early preventive action, vaccination, and continued surveillance will be essential to reducing the risk of infections and preventing potentially devastating neurological outcomes.
Reference:
https://kdca.go.kr/bbs/kdca/42/311453/artclView.do
For the latest on Japanese-Encephalitis, keep on logging to Thailand
Medical News.
Read Also:
https://www.thailandmedical.news/articles/infectious-diseases
https://www.thailandmedical.news/articles/dengue-news
Share
Tweet
Share
