Viral meningitis and encephalitis

Meningitis and encephalitis due to virus infections occur at all stages of life from the neonate to the elderly and may represent disease due to the primary site of replication, e.g. rabies, or be part of a wider infection syndrome, e.g. HIV. A large proportion of cases go unconfirmed by laboratory diagnosis despite use of sensitive techniques (such as the polymerase chain reaction). They may be both sporadic and epidemic in nature, but with changing environmental and societal conditions, agents may emerge anew, e.g. Nipah and Hendra viruses, or reappear after a period of good control through vaccination, e.g. mumps and poliovirus. Specific anti-viral treatment is very limited at present. Prevention is by public health measures and vaccination.