Japanese Encephalitis in Two Children—United States, 2010

Japanese encephalitis virus (JEV) is the leading cause of vaccine-preventable encephalitis in Asia and the western Pacific. JEV is maintained in an enzootic cycle involving mosquitoes and amplifying vertebrate hosts, mainly pigs and wading birds. The virus is transmitted to humans primarily by Culex mosquitoes, which breed in flooded rice fields and pools of stagnant water and most often feed outdoors during the evening and night. JEV transmission occurs mainly in rural agricultural areas, but occasional human cases occur in urban areas. Japanese encephalitis (JE) in persons who have traveled or lived overseas is diagnosed infrequently in the US, with only four cases identified from 1992 (when a JE vaccine was first licensed in the United States) to 2008. Here, Chen et al describe two case reports of JVE in US. Moreover, a CDC editorial note is included.