TAIPEI (Taiwan News) — Taiwan reported its youngest domestically acquired case of Japanese encephalitis, involving a three-month-old female infant in Hualien County, the Centers for Disease Control announced Tuesday.
The infant is not yet old enough to receive the Japanese encephalitis vaccine. Additionally, the infant and has no history of domestic or international travel or congenital diseases, per a press release.
In late May, the infant developed fever and lethargy and was taken to an emergency room, where she was hospitalized. During her stay, she continued to experience high fever and epileptic seizures. After testing, she was diagnosed with Japanese encephalitis and remains hospitalized.
Health authorities said no family members living with the infant have developed similar symptoms, and no high-risk areas have been identified near her residence. Health authorities have investigated her activities before illness onset, assessed potential risks, implemented prevention measures, and strengthened public health education in the area.
According to health data, Taiwan has recorded two confirmed cases of Japanese encephalitis this year. The disease's epidemic season typically runs from May to October, with infections peaking in June and July.
The number of confirmed cases nationwide during the same period from 2022 to 2025 was four, seven, 10, and three, respectively. While adults over age 40 have accounted for most cases, the CDC warned that people of all ages remain at risk and should take precautions.
Health officials said Japanese encephalitis in Taiwan is mainly transmitted by mosquitoes, including Culex tritaeniorhynchus, Culex annularis, and Culex pipiens labyrinthus. These mosquitoes commonly breed in rice paddies, ponds, and irrigation ditches.
Most people infected with Japanese encephalitis do not develop symptoms. Those who do may experience fever and headaches, while severe cases can involve altered consciousness, disorientation, weakness, coma, or death.
The public is advised to avoid high-risk mosquito areas, such as pig farms and animal shelters, during peak mosquito activity periods, including early mornings and evenings. If exposure cannot be avoided, people should wear light-colored long sleeves and use government-approved mosquito repellents containing DEET, picaridin, or IR3535 on exposed skin.
Health authorities said vaccination is the most effective way to prevent Japanese encephalitis. Taiwan's routine childhood vaccination schedule includes a first dose at 15 months of age, followed by a second dose 12 months later.
Parents are encouraged to take eligible children to local health centers or contracted medical facilities for vaccination on schedule to prevent serious complications from infection.
Adults who believe they may be at higher risk can visit travel medicine clinics for evaluation and receive self-paid Japanese encephalitis vaccinations if recommended.
More information is available on the CDC website or by calling Taiwan's epidemic prevention hotline at 1922 or 0800-001922.
