Epidemiological study of tick-borne encephalitis Serological study of rickettsia in Mongolian population

Abstract

Background: Tick-borne encephalitis is an infectious disease caused by RNA-containing virus belonging to the family Flaviviridae and genus Flavivirus. Objective of the research work: to detect rickettsial and borreliosis antibodies in the serum of tick-bitten participants and study risk factors of tick-borne infections. Materials and Methods: The study was conducted using a a cross-sectional study involving individuals. A total of 993 participants from 2016 to 2022, research data was collected through laboratory tests and questionnaires. 5 ml of blood was drawn from the peripheral vein of the individuals; serum was examined using the “TBEV IgM, IgG ELISA Antibody” album from EUROIMMUN Medizinische Labordiagnostika AG according to the manufacturer’s instructions, R software was used for statistical processing. Results: From 2016 to 2020, 993 participants under 75 years of age were included in the study and 8.1% (80/993) probable TBEV IgM cases and 20.2% (201/993) confirmed encephalitis cases were identified. According to logistic regression based on serum IgG, men had a 68% [OR: 2.25, 95% CI: 1.63-3.13] higher risk of developing tick-borne encephalitis than women (P < 0.001). The risk of contracting tick-borne encephalitis was significantly higher (P < 0.001) among the unemployed (35.0%, [OR: 0.51, 95% CI: 0.31-0.84]) than among the employed. The prevalence of tick-borne encephalitis in Ulaanbaatar City and the 16 provinces was highest in Selenge Province (40% (OR: 5.07, 95% CI: 1.73-21.7), Ulaanbaatar City (28%, [OR: 1. 5795% CI: 0.51-6.89]), the lowest prevalence was found in Bayan-Ulgii province (0.5%, [OR: 1.33, 95% CI: 0.06-12.4]) and in Dornod province (0.5%, [OR: 0.72 95% CI: 0.03-6.24]). Conclusion: 8.1% of possible encephalitis cases (IgM) and 20.2% of confirmed encephalitis cases (IgG) were detected in the serum of all individuals who participated in the study. Gender, age, occupation, and place of residence were risk factors for encephalitis infection. The prevalence of tick-borne encephalitis was highest in Selenge province and Ulaanbaatar city, and lowest in Bayan-Ulgii and Dornod provinces.