On May 28, 2012, the Taiwan Centers for Disease Control (Taiwan CDC) announced this year’s first confirmed case of Japanese encephalitis in Taiwan.  The case is a 33-year-old male who resides in Tainan City.  On May 16, he developed fever and headache.  On May 17, his symptoms persisted after seeking medical attention.  On May 18, when his symptoms worsened and he developed changes in consciousness, he was referred to a medical center and hospitalized. On May 22, Japanese encephalitis infection was confirmed in the case by Taiwan CDC.  As of now, the case is stable, but still hospitalized.  

According to Taiwan CDC’s surveillance data, transmission of Japanese encephalitis in Taiwan occurs annually between May and October and it usually peaks between June and July.  The incubation period for Japanese encephalitis is generally 5-15 days. In severe cases, psychological or neurological sequelae, and even death may occur. The primary vector of Japanese encephalitis is a species of mosquito, Culex tritaeniorhynchus.  The vector mosquitoes are most active during dawn and dusk.  Pigs act as the amplifying host for Japanese encephalitis.

Japanese encephalitis vaccine has been proven the most effective in preventing Japanese encephalitis. To maximize the effect of prevention, vaccination is mostly available from March to May every year and can be extended to September. A 2-dose regimen for routine childhood Japanese encephalitis vaccination is recommended for all toddlers aged 15 months and the 2 doses should be given two weeks apart. A booster dose should be given one year after the 2-dose primary vaccination. A second booster should be administered when the child attends first grade at elementary school.  Parents are urged to make sure their children are vaccinated against Japanese encephalitis at local health centers or designated hospitals.  Beginning 2013, children aged above 5 is recommended another booster dose before starting elementary school.  Adults who are at risk for Japanese encephalitis infection can consider receiving self-paid vaccines (approximately NT$250~500) at one of the 22 general hospitals in the nation, National Taiwan University Hospital Yun-Lin Branch, or National Yang-Ming University Hospital.  

As the Japanese encephalitis season is upon us and the vector mosquitoes are most active during the summer months, Taiwan CDC reminds the public to avoid mosquito bites by limiting visits to vector-prone areas such as pig and other animal farms.  If, however, visits to vector-prone areas are unavoidable, please wear light-colored clothing, long sleeves and long pants and apply officially approved mosquito repellent to exposed parts of the body to prevent mosquito bites and lower the risk of infection. For any questions or further information on Japanese encephalitis, please call the toll-free Communicable Disease Case Reporting and Consultation Hotline 1922, or 0800-024582 if calling from a cell phone, or visit the Taiwan CDC’s website: http://www.cdc.gov.tw.