Epidemics of
encephalitis occurring throughout much of Asia are caused by Japanese encephalitis virus (JEV), a flavivirus maintained in a zoonotic cycle and transmitted by the mosquito, Culex tritaeniorhynchus. Resident populations, including short-or long-term visitors to enzootic regions, are at risk for
Japanese encephalitis (JE)
infection and disease. For the past several decades, effective killed
viral vaccines prepared in tissue culture or mouse brain have been used to immunize travelers and residents of affected countries. Cost, efficacy, and safety concerns led to the development of a single-dose live attenuated virus
vaccine (SA14-14-2) and more recently, to the licensure in the United States, Europe, and Australia of a purified inactivated, tissue culture-based JE
vaccine (IC51; Intercell AG, Vienna, Austria) and the soon-to-be-licensed live-attenuated
yellow fever-JE chimeric
vaccine (
ChimeriVax-JE; Sanofi Pasteur, Lyon, France). Safe and effective JE
vaccines are now available to the entire at-risk population and should greatly diminish the burden of disease.