Nationwide 'Japanese Encephalitis' Alert... Vaccination Recommended for Those Born After 2011

The Korea Disease Control and Prevention Agency (KDCA) issued a nationwide Japanese encephalitis alert on the 25th. They urged the public to follow Japanese encephalitis prevention guidelines and for those eligible for vaccination to get vaccinated.

According to the KDCA on the 26th, the operation results of the Japanese encephalitis mosquito surveillance system showed that on the 24th of this month, the Japanese encephalitis vector mosquito, Culex tritaeniorhynchus, accounted for 63.2% and 58.4% of the total mosquitoes in Gyeongnam and Jeonnam, respectively, meeting the criteria for issuing an alert.

Culex tritaeniorhynchus is a small, dark brown mosquito that inhabits rice paddies, animal barns, puddles, and other areas. It is primarily active at night and is found throughout South Korea.

Adult female of Aedes japonicus. The 'Aedes japonicus', a mosquito vector of Japanese encephalitis, is generally dark brown with no distinct patterns and has a wide white band in the center of its proboscis.
[Photo by Korea Disease Control and Prevention Agency]

Infection with the Japanese encephalitis virus, a Class 3 notifiable infectious disease, usually causes mild symptoms such as fever and headache. However, in rare cases where it progresses to encephalitis, severe symptoms such as high fever, seizures, neck stiffness, confusion, convulsions, and paralysis may occur, with a fatality rate of 20-30%.

Especially when encephalitis develops, even if symptoms improve, 30-50% of patients may suffer from various neurological complications depending on the affected areas.

Approximately 20 cases of Japanese encephalitis occur annually in South Korea. Most first cases are reported in August and September, with cases sometimes appearing until November. From 2019 to 2023, a total of 91 cases were reported, with those aged 50 and above accounting for 87.9% (80 cases) of all patients. By region, Gyeonggi, Seoul, and Gangwon had the highest number of cases.

Symptoms were most commonly reported as fever, changes in consciousness, encephalitis, and headache. Complications such as cognitive impairment, motor dysfunction, paralysis, and speech disorders (multiple responses possible) were confirmed in 74% (67 cases) of all patients.

The KDCA recommends that those born after 2011, who are eligible for the national immunization program, receive vaccinations according to the standard immunization schedule, as effective vaccines against Japanese encephalitis are available.

Ji Young-mi, head of the KDCA, stated, "During the summer, outdoor activities increase the likelihood of exposure to Japanese encephalitis vector mosquitoes, so special care should be taken to avoid mosquito bites, and those eligible for vaccination should receive the vaccine according to the vaccination schedule."

This content was produced with the assistance of AI translation services.