Natural-Focal Viral Fevers in the South of the European Part of Russia. Crimean-Congo Hemorrhagic Fever

Abstract

Objective of the study was to determine the modern epidemiological peculiarities of Crimean-Congo hemorrhagic fever in the south of the Russian Federation.Materials and methods. Data of statistical documentation (epidemiological survey of the infectious disease focus, annual summary reports dated 2010–2019) and epizootiologic monitoring data submitted by the Rospotrebnadzor Administrations and the Centers of Hygiene and Epidemiology in the constituent entities of the Southern and the North Caucasian Federal Districts were used. Descriptive, genetic, analytical methods and retrospective epidemiological analysis were applied.Results and discussion. The СCHF natural focus in the European south of Russia has an area of 815 thousand square kilometers and it is characterized by persistence, expansion of the territory, and circulation of CCHF virus European genotypes. CCHF virus genetic variants form the local overlapping populations. Over the period of 2010–2019 997 CCHF cases were registered. Moderate forms of the disease clinically prevailed (74.2 per cent). Hemorrhagic symptoms were noted in 29.3 % of patients. The lethal outcome of the disease was registered in 31 CCHF patients (3 %). Two cases of nosocomial infection were identified, nine health workers were infected by CCHF pathogen. The expansion of epizootically active territory of the CCHF natural focus is associated with the expansion of the Hyalomma marginatum ticks area northward due to the aridization of the steppes, in part because of global climate change. The stability of the CCHF virus population was noted. The epidemic core of the CCHF natural focus remains on the adjacent territory of the Rostov Region, Stavropol Territory and the Republic of Kalmykia. The higher efficiency of CCHF prevention measures on the territory of the core is stemming from the targetness and intensity of measures, contributing to the early seeking of medical care by patients, their early hospitalization which in its turn influenced the development of clinical manifestations and outcome of the disease, and also made it possible to minimize the CCHF nosocomial infections number, including those among the medical personnel.