[The biology of the Ixodes ricinus tick].

More than 800 tick species have been reported world-wide however only about 30 tick species feed on humans, among them Ixodes ricinus, which is the most frequent tick species biting humans in Europe. It is the vector of Borrelia burgdorferi, which causes Lyme disease and of the tick-borne encephalitis virus. I. ricinus ticks pass through three developmental stages: larvae, nymphs and adults (females and males). More than 300 animal species have been reported as natural hosts for I. ricinus and 50 vertebrate species have been identified as reservoir hosts for B. burgdorferi. The density of this tick species may be very high, reaching in some places more than 300 ticks/100 m2. Attached ticks should be removed without delay with a blunt forceps.