Analysis of the Causes and Conditions for the Formation of a High Incidence of Acute Respiratory Infections (ARI) in the Population of the Altai Krai (Part 1. Features of Long-Term and Intra-Annual Dynamics of ARI Incidence in 2011–2021)

Relevance. The Altai Krai (AK) is among the least prosperous subjects of the Russian Federation in terms of the incidence of acute respiratory infections (ARI).Aim: to analyze the causes and conditions for the formation of a high incidence of ARI among the population of the Altai Krai based on an assessment of the long-term and intra-annual dynamics of the epidemic process in 2011–2021.Materials and methods. In the course of a retrospective epidemiological study according to the annual forms No. 2 of the state statistical observation (SOS) for 2011-2021 a comparative analysis of the incidence of ARI and community-acquired pneumonia (CAP) in various groups of the population of the AK, the Siberian federal district (SFD) and the population of the Russian Federation as a whole was carried out. Data for 2020–2021 («covid» period) was analyzed separately in comparison with the precovid period of 2011–2019. The intra-annual dynamics of the incidence of ARI and CAP in the AK were studied using the method of trend-seasonal decomposition according to the monthly forms No. 2 of the SOS.Results and discussion. It is established that in 2011–2021. the epidemic process of ARI in the AK was characterized by a higher level and rate of increase in the incidence of all population groups (adults and children, urban and rural) compared to the all-Russian and average for the Siberian Federal District; a higher proportion of children in the overall structure of ARI cases, despite the fact that the proportion of the child population did not exceed (or was even less) than in other regions; no decrease in the incidence of ARI in children in the period 2020–2021; the presence of a trend towards an increase in the incidence of ARI in both urban and rural residents in the pre-covid period; higher incidence in the rural population in 2011–2019 compared to the whole of the Russian Federation or the Siberian Federal District. A less pronounced role of the seasonal component in the registration of CAP was revealed, in comparison with ARI. In some years, an increase in the registration of CAP was observed in the spring-summer period. For 2020-2021 there was a close coincidence of the curves of the intra-annual dynamics of the registered incidence of ARI and COVID-19 among the general population, CAP and COVID-19.Conclusion. The obtained results indicate the need to study the possible impact of environmental factors, as well as the shortcomings of the etiological interpretation and differential diagnosis of some natural focal and zoonotic infections that occur with fever and respiratory symptoms on the formation of a high incidence of ARI in the Altai Territory.