Incidence and trends of ixodid tick-borne borreliosis and Siberian tick typhus in the Eastern Transbaikalia

Abstract

Aim. To study the trends and to assess longterm incidence of ixodid tick-borne borreliosis (ITB) and Siberian tick typhus (STT) in Eastern Transbaikalia for the improvement of preventive measures.Materials and Methods. We carried out a retrospective analysis of ITB and STT incidence in different districts of the Eastern Transbaikalia during 2003–2021. Epidemic trends were characterised using linear regression equations.Results. Average annual incidence of ITB in 2003–2021 was 4 cases per 100,000 population. Analysis of two periods (2003–2012 and 2013– 2021) showed an increase in ITB incidence in 2013–2021 (5.1 ± 0.79 per 100,000 population) as compared to 2003–2012 (2.6 ± 0.73 per 100,000 population, p < 0.05). Within 2013–2021 period, there has been a statistically insignificant trend towards decreasing ITB incidence. The incidence of STT was lower than that of ITB and there was no statistically significant trend towards change of this scenario (average annual incidence in 2003– 2021 was 2.1 ± 0.37 per 100,000 population). Between 2012 and 2021, in particular before 2017, the incidence of STT reduced (average annual incidence in 2012–2021 was 1.5 ± 0.43 per 100,000 population). The epidemiological risk of ITB and STT varied across the distinct territories of Eastern Transbaikalia.Conclusion. In order to prevent the incidence of tick-borne diseases, acaricide treatments should be regularly carried out. Amounts of such interventions should be determined depending on the risk of human infection.