Prevalence of Some Bacterial and Viral Pathogens in Ixodid Ticks Collected in Northwest Russia

Introduction: Ticks are among the most common vectors of pathogens that cause infectious diseases in humans. According to official government statistics, tick-borne infections are the most common zoonotic diseases in Russia, particularly in the Northwestern Federal District.

Objective: To detect the prevalence of Borrelia burgdorferi sensu lato, Rickettsia spp. SFG, Ehrlichia chaffensis/ E. muris, Coxiella burnetii, tick-borne encephalitis virus, and Anaplasma phagocytophilum in ixodid ticks collected in the Arkhangelsk, Leningrad, and Pskov regions, the Republic of Karelia, and the city of St. Petersburg.

Materials and methods: We tested 3,585 adult ixodid ticks of two species: Ixodes ricinus (48 %) and Ixodes persulcatus (52 %). Questing ticks were collected from vegetation by flagging and then tested individually by real-time PCR for genetic markers of tick-borne pathogens using commercial test systems and following the manufacturer’s instructions.

Results: 35.8 % of the collected ticks contained the genetic material of at least one pathogen. The prevalence of B. burgdorferi s.l. was 24.7 %; Rickettsia spp. SFG – 10.1 %; E. chaffensis/ E. muris – 6.9 %; C. burnetii – 5.1 %; tick-borne encephalitis virus – 2.1 %, and A. phagocytophilum – 1.1 %. Multiple pathogens were detected in 8.4 % of the ticks in 15 different combinations, the most common being B. burgdorferi s.l. + E. chaffensis/E. muris (3.5 %) and B. burgdorferi s.l. + Rickettsia spp. SFG (2.7 %).

Conclusions: Our findings show the existence of active natural foci of tick-borne infections in the Northwestern Federal District and justify the expediency of continuous monitoring of the prevalence of tick-borne pathogens in ixodid ticks.

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