[Tick-borne encephalitis--an update].

Tick-borne encephalitis (TBE) is a systemic infectious disease with nonspecific symptoms and/or severe neurological disorders such as meningitis, encephalitis and myelitis. The disease is caused by TBE virus, an enveloped RNA virus belonging to the family of flaviviruses. Three subtypes are currently present in different parts of Europe and Asia. The TBE virus is transmitted to humans primarily by the tick bite of Ixodes species such as I. ricinus, but also by the ingestion of contaminated raw milk and raw milk products. In Germany, more than 75% of all TBE cases occur in Bavaria and Baden-Württemberg (southern Germany). Depending on the region, 1 to 4% of adult I. ricinus ticks in southern Germany are infected with the central European TBE virus variant. Treatment of TBE is symptomatic and supportive, a specific antiviral therapy does not exist. TBE cases acquired in central European countries have usually a good prognosis. Mortality rates above 2% have been documented in cases of tick-borne encephalitis in the elderly. In endemic areas, active immunization with inactivated TBE virus vaccines provides the most secure protection against TBE. In addition, exposure prophylaxis (protection against tick bites) plays a crucial role for TBE prevention.