[Tick-born encephalitis].

INTRODUCTION: Tick-borne encephalitis (TBE), a disease contracted through tick bites, is caused by a Flavivirus. Its geographical distribution comes from the geographical distribution of the reservoir of infection--i.e., mainly the tiny mammals living in the forests and bushes. The endemic area spreads from the Rhine to the Urals, from Scandinavia to Italy and Greece. CURRENT KNOWLEDGE AND KEY POINTS: Symptoms usually evolve in three phases: at first a nonspecific phase with fever and myalgia, then an afebrile phase, and finally a phase with neurological manifestations, such as meningitis, meningoencephalitis and/or myelitis, and fever. Motor neurological sequelae are possible. The cases occurring in the East are characterized by their greater severity compared to those occurring in the West. The diagnosis, easily established given a history of a tick bite in an endemic area, is confirmed by the presence of specific IgM in the blood and/or cerebral spinal fluid. FUTURE PROSPECT AND PROJECTS: There is no specific treatment. Prevention consists of individual prophylactic measures (self-examination and systematic extraction of ticks after exposure, use of repellents), and in immunization. The vaccine, prepared from inactivated viruses, should be used for target populations, that is, for people exposed to tick bites during their professional or leisure outdoor activities.