Analysis of epidemic process manifestations and detection of pathogens’ markers of tick-borne infections in the Tomsk region

Abstract

BACKGROUND: Among the spectrum of the tick-borne infections, Lyme borreliosis (LB) and tick-borne encephalitis (TBE) are most often recorded in the Tomsk region, however it is obviously that possible range of the pathogens is not limited to these ones. AIM: is to assess epidemic process manifestations and detect frequencies of pathogen’s markers of tick-borne infections among adult patients applying serological and molecular genetic techniques in the Tomsk region during 2020–2023. METHODS: A single-center prospective sample study was conducted applying a comprehensive approach in peripheral blood specimens obtained from 197 patients with suspected tick-borne infections hospitalized during 2020–2023. To verify the diagnoses of TBE or LB, specific immunoglobulins of classes M and G to the antigens of TBE virus and Borrelia burgdorferi s. l. were determined in paired blood serum samples applying enzyme-linked immunosorbent assay (ELISA). Additionally, the polymerase chain reaction (PCR) was used to detect genetic markers of TBE virus, B. burgdorferi s.l., B. miyamotoi, Rickettsia spp., Coxiella burnetii, and Francisella tularensis. Epidemiological surveillance data of incidence rates of tick-borne infections obtained from official reports were analyzed as well. MS Office Excel 2010 software was used to calculate frequency morbidity measures. RESULTS: We verified the final diagnosis of TBE in 52 (26.4%) patients, LB in 116 (58.9%) patients, co-infection of TBE and LB 15 (7.6%) patients, hard tick relapsing fever caused by B. miyamotoi in 8 (4.1%) patients, coinfection of Q fever caused by C. burnetii with TBE or LB in 4 (2.0%) patients, and coinfection of tularemia with TBE or LB in 2 (1.0%) cases. We identified markers of TBE and LB pathogens by PCR in 3.6% and 4.1% of the patients. Most number of individuals with tick bites, and the highest LB and TBE incidence rates were recorded in the suburbs of Tomsk. The age groups of 40‒59 years, and elderly people 60 years and older were predominated among the patients. CONCLUSION: It was found out that, in addition to LB and TBE, there were such tick-borne infections as tick relapsing fever, Q fever, and tularemia in the Tomsk region in the 2020–2023 period.