ECOLOGY OF IXODES TRIANGULICEPS AND ITS SIGNIFICANCE IN NATURAL FOCI OF IXODID TICK-BORNE BORRELIOSES IN THE MIDDLE URALS

During 1994-2011, in natural foci of ixodid tick-borne borrelioses (ITBB) in the Middle Urals (Chusovskoi district, Perm Krai), more than seven thousand small mammals were collected and examined. Along with the main vector of Borrelia, the taiga tick (Ixodes persulcatus), about six thousand feeding I. trianguliceps were found. The I. trianguliceps abundance was about five times lower than that of I. persulcatus. I. trianguliceps was found 011 19 species of small mammals. Sorex araneus, Clethrionomys glareolus and C. rutilus are the main hosts of this tick. I. trianguliceps is characterized by two seasonal peaks in abundance: spring-summer and summer-autumn. Inoculation on the BSK-II medium was used for the examination of 1142 specimens of I. trianguliceps. Seventy-two isolates of Borrelia were obtained; sixty-four of them were identified using the polymerase chain reaction and the analysis of polymorphism of the restriction fragment length. The average infection with Borrelia for larvae, nymphs and adults off trianguliceps was 2.6, 10.2 and 8.1%, respectively. These values are 5-10 times lower than options obtained for the infection of larvae and nymphs of the taiga tick collected from the animals. Borrelia from I. trianguliceps (as obtained from I. persulcatus) assigned to the Borrelia garinii and B. afzelii. The first of these spirochetes is more common; about 90% of the isolates from I. trianguliceps were assigned to this species. These data suggest an involvement of I. trianguliceps to the circulation of ITBB pathogens in the forests of the Middle Urals. The low abundance of this tick and low infestation with borreliae indicate that I. trianguliceps cannot affect significantly on the dynamics of the epizootic process in natural foci of ITBB.