Japanese encephalitis – Korea South

The Korea Centers for Disease Control and Prevention (KCDC) confirmed the first case of Japanese encephalitis in Korea this year on August 30th. The case is a woman in her 40s living in Sejong City. She had no underlying disease other than an ovarian cyst and had no history of Japanese encephalitis vaccination.

An epidemiological investigation is currently in progress to confirm the location of the infection. Japanese encephalitis can be transmitted when bitten by a mosquito carrying the virus, and clinical symptoms occur in about 1 in 250 people, some progress to fatal acute encephalitis, 20 to 30% die, and 30 to 50 percent of survivors will have neurological, cognitive or behavioral sequelae.

Vaccination is recommended for adults who have never been vaccinated against Japanese encephalitis in the past and among those who live in areas with a high risk of Japanese encephalitis vector mosquitoes and who plan to travel to countries with Japanese encephalitis.

Photo: Culex mosquito.

Japanese encephalitis is an infection of the brain caused by the Japanese encephalitis virus. While most infections result in little or no symptoms, occasional inflammation of the brain occurs. In these cases, symptoms may include headache, vomiting, fever, confusion and seizures. This occurs about 5 to 15 days after infection.

The virus is generally spread by mosquitoes, specifically those of the Culex type. Pigs and wild birds serve as a reservoir for the virus. The disease mostly occurs outside of cities.

Prevention is generally with the Japanese encephalitis vaccine, which is both safe and effective. Other measures include avoiding mosquito bites. Once infected, there is no specific treatment, with care being supportive. Permanent problems occur in up to half of people who recover.

The disease occurs in Southeast Asia and the Western Pacific. bout 68 000 symptomatic cases occur a year, with about 17 000 deaths. Often, cases occur in outbreaks.

The disease was first described in Japan in 1871. Despite its name, the disease is now relatively rare in Japan as a result of large-scale immunization efforts.

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