The first human case of Japanese encephalitis in 2009 has been confirmed by Taiwan Centers for Disease Control (Taiwan CDC). This year, the first case has occurred earlier than that in previous years. Therefore, Taiwan CDC urges people to be on guard and prevent mosquito bites, and reminds parents to protect children aged 15 months and above with vaccination.

The case is a male who was born in 1956, lives in Pingtung County, and works in Kaohsiung County during the day. He developed symptoms, including fever and vomiting, since April 4 and he visited a clinic on the same day but his symptoms persisted.On April 8, when he experienced nuchal rigidity and some signs of meningitis, he visited the clinic again and was reported to the health authority as suspect case of Japanese encephalitis.The case was later confirmed on April 10, and is still hospitalized now. According to the investigation conducted by the health bureau, the case has not been vaccinated and has not traveled abroad recently. No suspected signs and symptoms are found in the family members of the case.

According to the epidemiological data, the annual Japanese encephalitis transmission season in Taiwan occurs between May and October and peaks in June and July. Previous statistics collected over the past decade by Taiwan CDC indicate that most confirmed Japanese encephalitis cases experienced onset during May to October, and the first confirmed case occurred after May every year. This year, the first confirmed case of Japanese encephalitis occurred one month earlier than before. People are urged to stay vigilant against mosquitoes.

The incubation period for Japanese encephalitis is 5 to 15 days. While the majority of patients with infections are asymptomatic or have mild symptoms such as headache, fever or aseptic meningitis, more severe infection is marked by headache, high fever, coma and convulsion, and might lead to mental sequelae or even death. In Taiwan, Japanese encephalitis is mainly spread by infected Culex tritaeniorhynchus and Culex annulus mosquitoes. The vectors’ favorite breeding sites include rice paddies, irrigation trenches, wet grasslands and large containers. The mosquitoes are more active at dawn and dusk.

Japanese encephalitis vaccine has been proven effective in preventing the disease. Every year, vaccination is primarily available from March to May, but can be extended through September. A 15-month toddler should be vaccinated with 2 doses 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. Adults can visit 26 hospitals of the Department of Health (DOH) for self-pay vaccination if needed. Taiwan CDC urges parents to have their children vaccinated against Japanese encephalitis on time. To prevent infection, avoid visiting vector-breeding sites such as pigpens at dawn and dusk when mosquitoes are most active. When needing to visit mosquito-prone places, people are advised to wear long-sleeved shirts and long pants, and apply mosquito repellent to exposed body parts to prevent mosquito bites and lower the risk of contracting Japanese encephalitis.

For more information about Japanese encephalitis, please visit the Taiwan CDC web site at http://www.cdc.gov.tw or dial the toll-free hotline, 1922, operated by Taiwan CDC.