Genetic Diversity of Tick-Borne Pathogenes in Tomsk and Environs

Two urban and two suburban biotopes of Tomsk were studied for tick-transmitted disease prevalence in ticks collected in the wild. Tick-borne encephalitis virus (TBEV), West Nile virus (WNV), Borrelia spp., Rickettsia spp., and Ehrlichia spp. were found in 6.5%, 2.2%, 8%, 2.5%, and 1.7% of tick specimens, respectively. Genetic markers of Powassan virus, Bartonella spp., and Babesia spp. were not found. Analysis of the genetic diversity of revealed pathogens demonstrated that TBEV strains belonged to the Siberian and Far-Eastern subtypes, and the Far-Eastern subtype of TBEV is most frequently found in urban biotopes (up to 43% of urban strains of TBEV). WNV strains belonged to the 1a genotype. Borrelia spp. was classified as B. garinii, Rickettsia spp. was classified as R. tarasevichiae and probably as a new Rickettsia raoultii subspecies, and Ehrlichia spp. was classified as E. muris. The coexistence of several pathogens was found in 5.7% of tick specimens, and TBEV + Borrelia spp. was the most frequent combination.