Epidemiological and Molecular Genetic Analysis of Outbreaks of Acute Intestinal Infections in the Khabarovsk Krai in 2022

Abstract

Introduction: Acute intestinal infections are amongst the most important health concerns worldwide. The majority of them are caused by viruses spread through environmental objects contaminated with feces. A high incidence of intestinal infections is registered annually in the Far Eastern Federal District of the Russian Federation. Over 50 % of cases of established etiology are induced by rota- and noroviruses. Moreover, outbreaks of viral intestinal infections are registered annually in almost all regions of the Far Eastern Federal District, including the Khabarovsk Krai. Objective: To analyze the incidence of acute intestinal infections and the results of molecular genetics testing of intestinal viruses that caused the outbreaks in the Khabarovsk Krai in the year 2022. Materials and methods: We used epidemiological and statistical methods to analyze the incidence and conducted molecular genetics testing of samples obtained from patients with acute intestinal infections and their contacts in the foci of the disease in the Khabarovsk Krai. Results: The acute intestinal infection situation in the Khabarovsk Krai in 2022 was unfavorable. The regional incidence rate was 20.6 % higher than that in the Far Eastern Federal District, with most diseases induced by intestinal viruses and numerous outbreaks registered. Our epidemiological investigation of six outbreaks revealed the fecal-oral transmission route of infection through contaminated food, household contacts and, probably, water. Molecular genetics testing of the causes of outbreaks showed circulation of norovirus genotypes GII.4Sydney[P16], GII.4Sydney[P31], GII.17[P17], and GII.6[P7] as well as rotavirus A genotypes G9P[8], G4P[8] and G3P[8] in the Khabarovsk Krai. Some of the identified norovirus genotypes had already caused outbreaks in the Khabarovsk Krai: GII.17[P17] – back in 2015 among the population of the Mnogovershinny village, GII.6[P7] – in the years 2018 and 2019 in the city of Khabarovsk, thus indicating long-term circulation of these genotypes. Conclusion: Surveillance over changes in genetic diversity of the viral population is required to evaluate contribution of various gene variants of rota- and noroviruses to the incidence of acute intestinal infections. In this regard, molecular typing of rota- and noroviruses should be performed not only when investigating disease outbreaks, but also when sporadic cases are registered.