[Infectious encephalitis].

Infectious encephalitis is a severe disease of the central nervous system with high case fatality ratio and long-term sequels. Although a high proportion remains unexplained, the most frequently identified cause in all countries was always herpes simplex virus type 1. The generalisation of acyclovir dramatically improved the survival rate of herpes simplex encephalitis patients. However, a high proportion of patients still experience neuropsychological sequels. Bacteria are a usual cause of encephalitis in France. Mycobaterium tuberculosis and Listeria monocytogenes in particular should be considered in the early treatment of encephalitis patients at the time of admission. Auto-antibodies encephalitis and ADEM, although not infectious diseases, can mimick viral encephalitis and should be included in the differential diagnosis of encephalitis patients.