Ticks and Tick-Borne Pathogens in Karelia: Analysis of Ticks Brought by Citizens to be Tested at the Center for Hygiene and Epidemiology in the Republic of Karelia (Petrozavodsk)

The species composition of the ticks brought by citizens to the Center for Hygiene and Epidemiology in the Republic of Karelia (Petrozavodsk) was studied in 2019 and 2021. About 2500 tick specimens were identified as belonging to 6 species of the family Ixodidae: Ixodes persulcatus Schulze, 1930, I. ricinus (Linnaeus, 1758), Dermacentor marginatus (Sulzer, 1776), D. reticulatus Fabricius, 1794, Hyalomma marginatum Koch, 1844, and Rhipicephalus sanguineus (Latreille, 1806). For 2% of the ticks, including all the species not distributed in Karelia, the attacks occurred outside of Karelia. Two species were identified from various districts of Karelia: I. persulcatus (about 95% of all the specimens) and I. ricinus. Pathogens were detected in ticks by real-time PCR, using an AmpliSens® TBEV, B. burgdorferi sl, A. phagocytophilum, E. chaffeensis / E. muris-FL commercial kit. The prevalence of the tick-borne encephalitis virus in I. persulcatus was 1.5%, while the virus was not detected in I. ricinus. The prevalence of the Borrelia burgdorferi s. l. and Ehrlichia spp. complex constituted 32.5 and 3.3% in I. persulcatus vs. 16.3 and 0.8% in I. ricinus, respectively. Anaplasma phagocytophilum was detected in a single specimen of I. persulcatus, resulting in a prevalence of 0.04%. The epidemiological situation in Karelia is mainly determined by the wide distribution and high abundance of I. persulcatus.