The Diversity of Spotted Fever Group Rickettsia Found in Ixodidae Hard Ticks Removed from Humans in Karachay-Cherkessia, North Caucasus, Russia

Karachay-Cherkessia is the region in the Russian Federation that has been overlooked in terms of research on the human bacterial pathogens transmitted by ticks. In this study, we investigated the infection status of ticks with Rickettsia, Borrelia, Coxiella burmetii, Anaplasma phagocytophilum, and Ehrlichia chaffeensis/Ehrlichia muris associated with natural focal infections in Karachay-Cherkessia. A total amount of 159 ticks from three species across three genera (Ixodes ricinus, Dermacentor marginatus, Hyalomma scupense) removed from humans were collected for analysis. Additionally, we used 53 individual ticks and 40 tick pools from the vegetation of three species (I. ricinus, D. marginatus, and Rhipicephalus bursa). Screening of the studied pathogens was performed by using commercial qPCR kits. Sanger sequencing utilizing partial sequences of gltA and ompA genes was employed to identify the Rickettsia species. Our findings revealed the presence of DNA from five species within the spotted fever group Rickettsia, namely Rickettsia raoultii, R. slovaca, R. helvetica, R. monacensis, and R. aeschlimannii. Moreover, two distinct genotypes were identified within R. aeschlimannii, R. helvetica, and R. monacensis. Additionally, DNA from Borrelia burgdoferi s.l., B. miyamotoi, and A. phagocytophilum was detected in the tested ticks. This study provides valuable insights into the prevalence and the diversity of bacterial pathogens transmitted by ticks in the Karachay-Cherkessia region.