Analysis of the epidemic situation of tick-borne viral encephalitis in the Republic of Altai in 2000-2017

Abstract

Introduction. The Republic of Altai is one of the regions of the Siberian Federal District endemic for tick-borne encephalitis with high altitude mountain belts with characteristic landscape and climatic conditions. The purpose of this study is to analyze the epidemiological situation of tick-borne encephalitis in the Republic of Altai from 2000 to 2017. Material and methods. In conducting a retrospective epidemiological study, data from sanitary-epidemiological and medical services for 2000-2017 were used. Statistical data processing was carried out with the software “Statistica 12.0”, the construction and analysis of cartograms - with the software ArcGIS. Results. The average long-term incidence rate of this infection in the period from 2000 to 2017 amounted to 21.7 ± 0.76 0/0000, which is 2.2 times higher than the similar indexby for the SFO (10.1 ± 0.23 0/0000). The number of persons affected by tick infestation in the period from 2000 to 2017 increased 3.5 times from 517.7 ± 15.95 0/0000 to 1810.5 ± 28.62 0/0000, respectively (p <0.001). Ranking on the level of the average long-term incidence allowed identifying three groups of the potential risk of infection of the population. Discussion. The factor analysis revealed the presence of an inverse correlation between the incidence of tick-borne encephalitis and the levels of seroprophylaxis (r = -0.93), acaricidal treatments (r = -0.95), vaccination (r = -0.10). The calculated levels of these factors were determined according to the results of the construction of spatial models of their mutual influences, capable of reducing the number of cases in the region to 6 per year. Conclusion. An analysis of the epidemic situation based on factor analysis and spatial modeling of the mutual influence of factors made it possible to determine the necessary volumes of preventive measures to reduce the incidence of the population to a given level. Such a calculation may be applicable in an endemic region to ensure the medical and economic effectiveness of preventive measures.