Species Diversity of Ixodidae Tick-Borne Borrelioses Agents in <I>Ixodes persulcatus</I> Ticks in the Territory of the Khabarovsk Region

Abstract

The aim of the work was to determine the species diversity of the causative agents of Ixodidae tick-borne borrelioses in Ixodes persulcatus ticks in the Khabarovsk Territory.Materials and methods. During the epidemic season (April–October) 2017–2023, 4751 specimens of I. persulcatus Schulze, 1930, removed after attachment to humans and 418 ones collected from vegetation in the Khabarovsk Region, were studied. Ixodidae ticks were collected in the green areas of Khabarovsk city during the snowless season of 2021–2023, as well as in the territory of the Khabarovsk Region on the flag. DNA of the borrelia complex Borrelia burgdorferi sensu lato (s.l.) and B. miyamotoi was detected in ticks using real-time polymerase chain reaction (PCR). Differentiation of borrelia species in samples containing genetic material of B. burgdorferi s.l. was carried out in two stages. At the first stage, the presence of DNA from borrelia of the B. garinii s.l. group (B. garinii + B. bavariensis) and B. afzelii DNA was determined in the sample. At the second stage, positive samples of B. garinii s.l. were differentiated into B. garinii sensu stricto (s.s.) and B. bavariensis. Results and discussion. In engorged ticks, genetic material of B. burgdorferi s.l. was detected in 45.7 % of the cases, DNA of B. miyamotoi was identified in 7.2 % of samples. In ticks collected from vegetation, the DNA of B. burgdorferi s.l. was detected in 38.0 % of cases. Upon further study, the genetic material of B. afzelii and borrelia of the B. garinii s.l. group was identified in 47.2 % of cases for both pathogens. Within the group B. garinii s.l., DNA of B. bavariensis was detected in 18.6 %, B. garinii s.s. – in 8 % of samples, at the same time, mixed infection was noted in 53.3 % of cases. The infection rate with B. afzelii in I. persulcatus ticks turned out to be statistically significantly higher than that for B. garinii s.s. and B. bavariensis, thereat statistically significant differences in tick infection rates with B. garinii s.s. and B. bavariensis was not detected.