The Taiwan Centers for Disease Control (CDC) announced today the first confirmed domestic case of Japanese encephalitis for the year in a woman in her 60s residing in Minxiong Township, Chiayi County in southwestern Taiwan.
She has no recent history of overseas travel but has a history of chronic illness. In early June, she was hospitalized after developing symptoms such as fever, impaired consciousness, and coma; she was subsequently confirmed positive following hospital notification and testing and remains hospitalized.
Household members show no suspected symptoms.
The patient’s daily activities were primarily centered around her home, which is located near rice paddies and irrigation ditches, as well as high-risk sites such as pigeon coops, pig farms, and poultry farms.
Health authorities have installed mosquito-attracting light traps at the patient’s residence and nearby high-risk areas, stepped up health education for local residents, and reminded medical facilities to enhance case reporting.
In Taiwan, the Japanese encephalitis epidemic season runs from May to October, with the peak occurring between June and July. The number of confirmed cases nationwide during the same period from 2022 to 2025 was 2, 6, 8, and 1, respectively; while adults over the age of 40 account for the majority of cases, individuals of all ages are at risk of infection.
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The CDC stated that the primary mosquito vectors transmitting Japanese encephalitis in Taiwan (Culex tritaeniorhynchus, Culex annulus, and Culex fuscocephalus) frequently breed in rice paddies, ponds, and irrigation ditches.
Most people infected with Japanese encephalitis do not exhibit obvious symptoms. Those who do become symptomatic may experience headaches and fever; severe cases can lead to altered consciousness, disorientation regarding person, place, or time, and generalized weakness, potentially progressing to coma or death.
The public is advised to avoid activities in high-risk areas for vector mosquitoes—such as pigsties and other animal enclosures—during the insects’ peak biting times. If such activities cannot be avoided, individuals should wear light-colored, long-sleeved clothing and long trousers, and apply government-approved mosquito repellents containing DEET, Picaridin, or IR3535 to exposed skin.
The Centers for Disease Control (CDC) emphasizes that vaccination is the most effective method for preventing Japanese encephalitis. The standard vaccination schedule for young children involves receiving the first dose at 15 months of age, followed by a second dose 12 months later. Parents are reminded to take eligible children to local public health centers or contracted medical facilities for timely vaccination to prevent serious complications resulting from infection. Additionally, individuals living or spending time near high-risk environments—such as pigsties or rice paddies—should implement mosquito prevention measures; adults who perceive themselves to be at risk of infection may visit travel medicine clinics to evaluate the option of receiving the Japanese encephalitis vaccine at their own expense.
AloJapan.com