On May 11, 2016, the Taiwan Centers for Disease Control (Taiwan CDC) received a report of a suspected Japanese encephalitis case in a 56-year-old peasant woman who resides in southern Taiwan from a local health authority.　 On May 5, the case sought medical attention at a clinic after developing fever, headache, vomiting and lethargy. On the next day, when her fever persisted and she developed change of consciousness, she sought further medical attention at a hospital and was hospitalized. After the hospital reported her to the local health authority as a suspected Japanese encephalitis case, infection was confirmed in the case by the Taiwan CDC laboratory on May 13. The case is this year’s first Japanese encephalitis case. As of now, the case is still unconscious and hospitalized.

According to relevant regulations, Japanese encephalitis is listed as as a Category III Notifiable Infectious Disease. The local health authority is in charge of reporting suspected cases and conducting the epidemiological investigation.　Through division of responsibilities between the central and local governments, not only can the disease surveillance be more timely, but also an outbreak can be more effectively controlled. 　 According to the epidemiological investigation, the case had not recently traveled overseas and the case spent most of her time at home and work area. In addition, there are chicken farms within 50 m of the cases residence and pig farms and rice paddy fields within 2 km of the case’s residence. Hence, it is determined that the source of infection is somewhere around the case’s residence. Currently, none of the family members residing in the same household has experienced any symptoms. To prevent the further spread of the disease, the local health authorities has set up mosquito lamps around the residence of the confirmed cases as an attempt to capture vector mosquitoes and reinforced health education among residents who live near the confirmed cases as well as urged routine vaccination of age-appropriate children.

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. 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. Thus far this year, as of May 13, 1 Japanese encephalitis case has been confirmed in Taiwan. During 2011 and 2015, the total numbers of confirmed Japanese encephalitis cases respectively are 22, 32, 16, 18 and 30. People of all ages can become infected. People aged between 30 and 59 are at increased risk for infection.

As vaccination is the most effective way to prevent Japanese encephalitis, people who live near or work in close proximity to pig farms or rice paddy fields that increase their risk of Japanese encephalitis infection are recommended to visit one of the hospitals under the Ministry of Health and Welfare for self-paid vaccination. In addition, Taiwan CDC also urges parents and caretakers of age-appropriate children who have not received the vaccine to get vaccinated as soon as possible at their local health center or designated medical institution to prevent infection and severe complications.　

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 light-colored, long-sleeved shirts and long pants, and apply officially approved mosquito repellent to exposed body parts to prevent mosquito bites and lower the risk of contracting Japanese encephalitis. For any questions or further information, please visit the Taiwan CDC’s website at http://www.cdc.gov.tw or call the toll-free Communicable Disease Reporting and Care Hotline, 1922 (or 0800-001922).