Encephalitis Caused by Viruses

Abstract

Viral encephalitis is a general term used to define a heterogeneous group of quite benign diseases, although some may be devastating. The extremes of the spectrum are benign autolimited affections, such as lymphocitic meningoencephalitis, and rabies, which leads to death in 100% of the cases. Incidence is variable and diseases may occur occasionally or in epidemics. The most common aetiology among sporadic encephalitis in the United States is the Herpes group, including Herpes Simplex Virus (HSV) type I, type II, and Herpes Zoster, and the most common aetiology causing epidemics are the insect-related arbovirosis. Beside those, the AIDS epidemic is responsible for the important increase in incidence of primary HIV encephalitis, causing the so-called AIDS-dementia complex and the immune-suppressive state which favours other viral encephalitis, such as the one caused by CMV or the ones related to the papova group.