Encephalitis caused by neurotropic viruses that are transmitted via the bite of TICKS. In Europe, the diseases are caused by ENCEPHALITIS VIRUSES, TICK-BORNE, which give rise to Russian spring-summer encephalitis, central European encephalitis, louping ill encephalitis, and related disorders. Powassan encephalitis occurs in North America and Russia and is caused by the Powassan virus. ASEPTIC MENINGITIS and rarely encephalitis may complicate COLORADO TICK FEVER which is endemic to mountainous regions of the western United States. (From Joynt, Clinical Neurology, 1996, Ch26, pp14-5).