Viral encephalitis

Encephalitic viruses first cause infection and replicate outside of the central nervous system (CNS), most reaching the CNS through the circulatory system and a minority from nerve endings toward the CNS. Once in the brain, the virus and the host's inflammatory response disrupt neural function, leading to illness and complications, many of which frequently are neurological in nature, such as impaired motor skills and altered behavior. Viral encephalitis can be diagnosed based on the individual's symptoms, personal history, such as travel history, and different clinical tests such as histology, medical imaging, and lumbar punctures. A differential diagnosis can also be done to rule out other causes of the encephalitis. Many encephalitic viruses often have characteristic symptoms of infection, helping to aid diagnosis. Treatment is usually supportive in nature while also providing antiviral drug therapy. The primary exception to this is herpes simplex encephalitis, which is treatable with acyclovir.