Genotyping of Borrelia, Rickettsia and Anaplasma in Ixodes ricinus and Dermacentor reticulatus ticks in the Kaliningrad region

Abstract

Background. Tick-borne bacterial and protozoal pathogens pose a significant public health problem. The aim of this study was to detect and genotype Borrelia, Rickettsia and Anaplasma in Ixodes ricinus and Dermacentor reticulatus ticks collected in the Kaliningrad region in 2021–2022. Materials and methods. The study included 862 I. ricinus and 803 D. reticulatus ticks (1665 in total) collected in 33 biotopes of the Kaliningrad region. Detection of the DNA of tick-borne pathogens was carried out in individual ticks by PCR using a set of specific primers, followed by sequencing and phylogenetic analysis. Results. The level of infection of I. ricinus ticks with Borrelia was 15.5%, and genotyping by the p66 gene sequence showed the presence of genetic material from four species: B. afzelii, B. garinii, B. valaisiana, and B. lusitaniae. In D. reticulatus ticks, no Borrelia genetic material was detected. The Rickettsia DNA has been found in both tick species. Moreover, the infection rate of I. ricinus ticks was 2.6%, and D. reticulatus — 21.2%. R. helvetica were found in I. ricinus ticks, and R. raoultii in meadow ticks when genotyping by gltA gene. Genetic markers of Anaplasma phagocytophilum have been found in I. ricinus and D. reticulatus ticks. Cases of co-infection of an individual tick have also been identified. Conclusion. Six different species of tick-borne pathogens were found in the I. ricinus and D. reticulatus ticks collected in the Kaliningrad region and R. helvetica, R. raoultii and A. phagocytophilum were identified for the first time.