Geno-Species Composition of Borrelia Circulating on the Black Sea Coast of the Krasnodar Territory

Abstract

The aim of the study was to assess the current epidemiological situation on Ixodidae tick-borne borreliosis (ITBB) (2017–2022) on the Black Sea coast of the Krasnodar Territory, to study the species composition of Borrelia.Materials and methods. Ixodidae ticks, Ixodes ricinus, Haemaphysalis concinna, H. inermis, Rhipicephalus sanguineus, were examined for infection with tick-borne borreliosis pathogens, followed by DNA sequencing of isolates. Species identification of Borrelia was carried out based on analysis of the nucleotide sequence of the 16S rRNA gene fragment using BLAST algorithm. Additionally, the OspC genotype was determined for isolates of pathogenic genovariants through comparing the obtained sequences with reference ones in the MEGA 5 program. The data were processed applying the cartographic method using the QGIS 2.18 software.Results and discussion. Between 2017 and 2022, 101 cases were registered on the Black Sea coast of the Krasnodar Territory, which accounted for 1.6 % of all ITBB cases in the Krasnodar Territory. The number of complaints with tick bites in Sochi was up to 191.4 per 100 thousand population. During the study, the predominant Borrelia geno-species on the territory of the Black Sea coast of the Krasnodar Territory was determined using sequencing – Borrelia lusitaniae (78.1 %). The circulation of geno-species B. garinii (6.8 %), B. valasiana (5.7 %), B. afzelii (3.6 %), B. miyamotoi (2.6 %), B. tanukii, B. bissettii (1.6 % each) was also observed. For Borrelia pathogenic species, appurtenance to OspC geno-groups was ascertained: four isolates were assigned to invasive OspC geno-groups, of which three B. afzelii isolates were genogroup A8, one B. garinii isolate was G7. High rate of infection of ticks with Borrelia was recorded in the surveyed area (up to 94.5 %). Borrelia of pathogenic species account for only 10.4 % of the total number of isolates studied. Mostly, genovariants that rarely cause diseases in humans (B. lusitaniae, B. valasiana, B. bissettii) and non-pathogenic Borrelia (B. tanukii) were found, which indicates a low risk of infection with ITBB pathogens.