Ticks and Tick-borne Infections in the Far East of Russia - Abstract
The vector-borne zoonosises remain public health concern especially in the Far East of Russia because of high population density of ixodid ticks and their biodiversity rearrangements due to anthropogenic pressure. Ixodes persulcatus Schulze, 1930 remains predominant in the isolated populations of the Sakhalin island and in continental wildlife reserves with its gradual displacement with other tick species near agro landscapes and towns. The infection rate of I. persulcatus with Rickettsia spp. (up to 100%) and Borrelia burgdorferi sensu lato (up to 69%) exceeded the corresponding frequencies of the tick-borne encephalitis virus (TBEV), Borrelia miyamotoi, Anaplasma, Ehrlichia, Francisella tularensis and Babesia spp. Phylogenetic analysis of the nucleotide sequences of the PCR products permitted to reveal genetic diversity of the tick-borne bacteria including Borrelia garinii, B. afzelii, B. miyamotoi, Rickettsia helvetica,
Candidatus Rickettsia tarasevichiae, A. phagocytophilum, E. muris, Candidatus Neoehrlichia mikurensis, Francisella tularensis found in I. persulcatus ticks and only B. burgdorferi s. l. complex and Rickettsia heilongjiangensis - in H. concinna. The TBEV isolates from ticks and mosquitoes of the predominant Far Eastern subtype appeared to be very stable since 1937. Besides the monoinfection the real time PCR with subtype specific fluorescent probes showed mixed infection of the TBEV Far Eastern subtype with Siberian subtype in the ixodid ticks. Molecular epidemiological monitoring allowed us to estimate risks of the tick-borne infections in the Far East of Russia and to reveal their genetic diversity necessary for the diagnostic systems and vaccines.