Generally speaking, encephalitis refers to an inflammation of the brain tissue.  Japanese encephalitis refers to a type of encephalitis that is caused by a virus and is the leading cause of encephalitis in Asia and the western Pacific. This type of encephalitis is vaccine-preventable, and the risk of contraction is low, but still a concern for those traveling to Asia.  The risk for exposure varies by destination, season and the types of activities someone is involved in.