Japanese Encephalitis Alert Issued Nationwide... Around 20 Infections Reported Annually

On the 27th, a Japanese encephalitis alert was issued nationwide.

Mosquito [Photo by Yonhap News]

According to the Korea Disease Control and Prevention Agency, the operation of the Japanese encephalitis mosquito surveillance system confirmed that on the 26th in Busan, the Japanese encephalitis vector mosquito, Culex tritaeniorhynchus, accounted for 91.4% (1,056 out of 1,155) of the total mosquitoes caught. This meets the alert issuance criteria of “when the daily average number of Culex tritaeniorhynchus mosquitoes collected twice a week is 500 or more and they constitute more than 50% of the total mosquito density.”

Culex tritaeniorhynchus, which transmits Japanese encephalitis, is a small, dark brown mosquito that inhabits rice paddies, animal barns, and puddles. Typically, their numbers begin to increase from June in the southern regions and occur throughout South Korea from July to September. They can be observed until the end of October. They mainly feed at night.

Every year, about 20 people contract Japanese encephalitis, mostly between September and October. The majority are aged 50 and above. Mild symptoms such as fever and headache appear, but in rare cases, if it progresses to encephalitis, severe symptoms such as high fever, seizures, neck stiffness, confusion, convulsions, and paralysis may occur, with a 20-30% mortality rate. Depending on the affected area, various neurological complications may also develop.

There is an effective vaccine for Japanese encephalitis. The KDCA recommends vaccination according to the standard immunization schedule for those eligible for national vaccination support. Vaccination is also recommended for people living in rural areas or near pig farms where Japanese encephalitis vector mosquitoes are prevalent. The same applies to those who plan to stay for 30 days or more in Japanese encephalitis risk countries such as Australia, Bangladesh, China, and India.

Last year, the alert was issued on the 23rd of the same month. A KDCA official explained, “This year’s alert was issued about a week later than last year, which is presumed to be due to the fact that the number of rainy days in Busan this year was 18, compared to 8 days last year.”

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