The role of particular tick developmental stages in the circulation of tick-borne pathogens affecting humans in Central Europe. 2. Tick-borne encephalitis virus

Hard-bodied ticks transmit various pathogens, such as Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum, Rickettsia spp., Babesia spp., and carry numerous other microorganisms with an unknown pathogenic potential. Among them, tick-borne encephalitis virus has great importance. In Central European conditions all developmental stages of ticks participate in the zoonotic cycle of the TBE virus. According to pathogen and tick biology, the roles of larvae, nymphs and adults are different. Larvae and nymphs of Ixodes ricinus ticks are responsible for circulation in rodents and medium sized mammals; adults transfer the infection to ruminants and to next generations via transovarial transmission. All active developmental stages of I. ricinus can play role of the bridge vector, transmitting the infection to humans apart males which don’t feed. The late summer peak of human infectivity is caused by the summer peak of I. ricinus nymphs’ activity. The Dermacentor reticulatus tick attacks humans infrequently, but does participate in the circulation of the virus in the zoonotic foci; larvae and nymphs of the D. reticulatus ticks are responsible for circulation in rodents, mainly Microtinae, while adults transmit the infection to ruminants.