[Clinical and epidemiological aspects of Japanese encephalitis]

Japanese encephalitis has been well controlled in Japan. On the other hand, the Japanese encephalitis virus (JEV) transmission cycle still exists, as does the risk of exposure to JEV infection. Although Culex tritaeniorhynchus has been considered the major mosquito vector in Japan, recent surveys suggested Culex pipiens complex and Aedes albopictus as potential alternatives. Similarly, swine have reduced the role in amplification of JEV in paradomestic environments. Another surveys suggested attenuation of recent JEV strains and a shift in the major clinical manifestation caused by JEV infection from encephalitis to meningitis. This paper describes current situation of Japanese encephalitis in Japan from clinical and epidemiological aspects.