Viral meningitis and encephalitis

Viral meningitis and encephalitis occur at all stages of life. They may represent disease at its primary site of replication (e.g. rabies) or be part of an infection syndrome (e.g. HIV). A large proportion of cases go unconfirmed by laboratory diagnosis despite use of all available laboratory techniques. They may be sporadic or epidemic, but with changing environmental and societal conditions, infective agents may emerge for the first time (e.g. Nipah and Hendra viruses) or reappear after a period of good control through vaccination (e.g. mumps virus and poliovirus). Specific antiviral treatment is limited at present. Prevention is by public health measures and vaccination.