The Prevalence of Japanese Encephalitis in Taiwan and Adjacent Countries

Yu-Ju Chen, Feng-Kuang Hsu, Li-Ching Hsu

2013 Vol.29 NO.3

Correspondence Author: Li-Ching Hsu

  • Research and Diagnostic Center, Centers for Disease Control, Taiwan


   The infection of Japanese encephalitis virus (JEV) is an important public health issue in Asia and Western Pacific regions with its infected area tending to enlarge. In tropical region, Japanese encephalitis (JE) is the main cause of acute encephalitis in children and adults. As long as clinical symptom appears, about 15% to 40% of cases die, and 30% to 50% of cases may have sequellae like permanent neural symptoms or mental disorders, bringing about poor prognosis. These will all greatly affect individuals, families and the society. Due to the JE vaccination program in children, the incidence rate has decreased apparently, and among all, Japan, Korea and Taiwan have shown the most remarkable effect. Japan and Korea have confirmed cases below ten in recent years, and Taiwan has 20 to 30 cases per year, which exceeds the two adjacent countries obviously. Though Taiwan, Japan and Korea's confirmed case numbers decreased with each passing year, they all face a problem that the main infected people have become adults and even elders, showing that in countries inoculating JE vaccine for a long period, their adults group becomes the newly high-risk group instead. This circumstance may be related to the group of people which had never been vaccinated, the decline of prolonged antibodies or the decrease of natural infection rate. Because that sequellae caused by the infection of JEV not only affect individual’s living quality, but also reduce social productivity and waste huge amount of medical cost. Currently, there are no specific anti-virus drugs available but only supporting treatments, and vaccination is known as the most effective method of preventing JEV infection at the present time.