Prevalence of Genetic Markers of Tick-Borne Diseases in Ixodid Ticks Collected in Various Landscape Zones of the Tyumen Region and the Khanty-Mansi Autonomous Okrug

Introduction: The wide distribution of ixodid ticks and their ability to preserve and transmit pathogens of many viral and bacterial infections determine the relevance of this study.
Objective: To characterize the structure and prevalence of genetic markers of vector-borne pathogens in Dermacentor reticulatus and Ixodes persulcatus ticks collected from vegetation in the Tyumen Region and in the middle taiga subzone of the Khanty-Mansi Autonomous Okrug.
Materials and Methods: We conducted a retrospective 16-year analysis covering the epidemic seasons of the years 2004, 2007–2011, 2013, 2015–2018, and 2021–2025 and including 5,473 adult taiga (I. persulcatus (n = 2,742)) and meadow (D. reticulatus (n = 2,731)) ticks collected from vegetation in the Tyumen Region and the Khanty-Mansi Autonomous Okrug by flagging. Tick species and sex were established. The presence of genetic markers of tick-borne encephalitis virus (TBEV), ixodid tick-borne borreliosis (ITBB), human monocytic ehrlichiosis (HME), and human granulocytic anaplasmosis (HGA) was detected in unpooled ticks using the polymerase chain reaction. We calculated long-term rates, analyzed nominal variables using the Pearson’s χ² test, visualized and systematized data in Microsoft Excel. Statistical analysis was performed using licensed IBM SPSS Statistics 22.0.
Results: The long-term study of ixodid ticks showed that D. reticulatus ticks were usually found in urbanized areas and parks of the Tyumen city, less often in the subtaiga and northern forest-steppe subzones. I. persulcatus ticks prevailed in the southern taiga subzone of the Tyumen Region and the middle taiga of the Khanty-Mansi Autonomous Okrug. In 2015, taiga ticks were found in Tyumen for the first time. Females and males dominated among I. persulcatus and D. reticulatus ticks, respectively. We observed markers of HME in 27.8 % and those of ITBB in 26.8 % of the taiga ticks collected in the northern forest-steppe subzone. Borrelia and anaplasma DNAs were detected in 1.8 % and 0.4 % of the meadow ticks collected in Tyumen. The ITBB DNA was found in 59.5 %, HME DNA in 14.6 %, HGA in 16.4 %, and TBEV RNA in 5.9 % of the I. persulcatus ticks collected in the southern taiga subzone while those collected in the middle taiga zone usually contained ITBB DNA (46.5 %), HME DNA (15.7 %), and TBEV RNA (7.1 %).
Conclusions: The findings demonstrate the leading role of I. persulcatus ticks in maintaining the epidemic activity of natural foci in the northern forest-steppe and southern taiga zones of the Tyumen Region and the middle taiga subzone of the Khanty-Mansi Autonomous Okrug.

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