Viral encephalitis.

Viral encephalitis represents an important source of morbidity and mortality worldwide. Numerous viruses possess neurovirulence, producing encephalitic disorders that usually consist of fever, headache, vomiting, altered consciousness, focal or generalized seizures, and motor dysfunction. Contemporary virologic methods frequently allow rapid and specific identification of viral pathogens, but the etiologic agent remains uncertain in 25% or more of encephalitis patients. Although acyclovir substantially reduces mortality and improves outcome for patients with herpes simplex virus encephalitis, supportive care remains the only therapy available for most patients with virus encephalitis.