Determinants of manifestations of the epidemic process of epidemic hemorrhagic fever in Primorsky Krai

Abstract

BACKGROUND: The contribution of random and regular factors in the process of epidemic hemorrhagic fever is unknown, which necessitates the search for the reasons for the formation of severe and fatal cases. AIM: Based on the incidence of epidemic hemorrhagic fever in Primorsky Krai over a long period, we aimed to establish the role of the main determinants of the epidemic process and to demonstrate the causality of local manifestations in epidemic foci in patients with epidemic hemorrhagic fever. MATERIALS AND METHODS: In this comprehensive descriptive epidemiological and clinical study, we undertook the epidemiological analysis of the incidence of epidemic hemorrhagic fever and data from examinations of the foci of infection. We performed a clinical observation (case study) of a case of epidemic hemorrhagic fever with a fatal outcome at the Regional Clinical Infectious Diseases Hospital in March 2022. The object of the study is statistical data on officially registered cases of epidemic hemorrhagic fever in Primorsky Krai from 1995 to 2021. RESULTS: The proportion of random factors in the epidemic process of epidemic hemorrhagic fever in the period under review was 28.7% of the incidence, which formed deviations from the typical curve, but did not participate in the formation of cyclicity in the long-term dynamics. Variable factors that formed cyclicity and random deviations together determined 53.4% of the incidence. They were fully related to seasonal morbidity (67.8%). Moreover, the remaining 14.4% of seasonality was formed by constant factors for each month. Factors constant for all months of the year form a year-round form, that is, 32.2% of the incidence. In the clinical and epidemiological observation of a lethal case of epidemic hemorrhagic fever, infection was noted under conditions of dust formation, such as when restoring order in a closed room at a negative temperature (sweeping) and high titers of specific antibodies resulting from repeated encounters with the pathogen in residential and occupational types of morbidity and the accompanying illnesses. CONCLUSIONS: The study of the incidence of epidemic hemorrhagic fever demonstrated a high resolution of epidemiological analysis by using a binary method in zoonoses. The patterns and features of human morbidity were controlled by natural and social factors more strictly than by biological ones. The determinants of the socio-ecological system in epidemic hemorrhagic fever in Primorsky Krai make it possible to specify the tactics and strategy for the implementation of epidemiological surveillance.