[Antiviral drugs].

Acute encephalitis is inflammation of the brain and meninges caused by direct invasion of pathogens into the central nervous system (CNS) (primary encephalitis) or immunopathological responses in the CNS (secondary encephalitis), while acute encephalopathy is characterized clinically by rapidly progressive brain damage following viral infection, and pathologically by brain edema in the absence of direct invasion of the virus and inflammatory cells. A number of pathogens have been associated with acute encephalitis/encephalopathy, including influenza viruses and human herpesviruses, although their involvement in the neuropathogenesis varies. Treatment of acute encephalitis/encephalopathy should be based on the etiological mechanism, and antiviral agents directly act against pathogens of primary encephalitis (e.g., herpes simplex encephalitis) and may alleviate encephalopathy by reducing antigenic burden (e.g., influenza-associated encephalopathy).