Analysis of coxsackievirus A6 circulation in the territories of the Far Eastern Federal district of the Russian Federation in 2014–2019

Introduction. Molecular epidemiological monitoring of enterovirus infection (EVI) in the territories of the Russian Federation showed that coxsackievirus A6 (CVA-6) had been one of the most prevalent types of enteroviruses that circulated among the country population during last years and had caused majority of EVI outbreaks. Objective — to evaluate coxsackievirus A6 circulation in the territories of the Far Eastern Federal district (FEFD) in 2014–2019 utilizing methods of molecular genetics. Materials and methods. RT-PCR was employed to detect enterovirus RNA in biological material collected in 9 territories of the FEFD . In order to establish enterovirus types, amplification of positive samples was carried out to detect nucleotide sequence fragments of the VP1 and VP2 genes. Molecular genetic analysis of the Far Eastern CVA-6 strains was based on detection of nucleotide sequences of VP1 and 3Dpol gene fragments. Phylogenetic trees were constructed by the means of Bayesian phylogenetic methods. Results. Total 1773 nucleotide sequences of 43 types of non-polio enteroviruses were obtained in 2014-2019. Majority of the sequences belonged to coxsackievirus A6 (524; 29.5%). In the years of the highest CVA-6 detection an increase in EVI incidence as well as EVI outbreaks were observed in the territories of FEFD. The most prevalent manifestations of EVI caused by CVA-6 in FEFD were herpangina and exanthemic forms. Phylogenetic analysis showed that Far Eastern strains of CVA-6 during in the analyzed period of time belonged to D3 subgenotype that is dominant in the world. The circulation of several recombinant forms of CVA-6 (RF-A, -H, -L, -N, -R) was also registered. Conclusion. The genetic diversity of CVA-6 strains circulating in the territories of the FEFD in 2014–2019 revealed in this study requires further investigation in order to obtain new knowledge about the CVA-6 molecular epidemiology and improve the enterovirus surveillance system

Retrospective Analysis of Enterovirus Infection Morbidity Rate in the Territory of the Amur Region and Peculiarities of Epidemic Process in the Period of Large-Scale Flood

There has been observed a tendency to increment of enterovirus morbidity rate over the past seven years. Foci of this infection have been formed in the area from time to time, with minor forms of the disease being predominant in clinical findings. Genetically enteroviruses circulating in the Amur Region have been characterized as homogenous; however there is a genetic relation among them with and, consequently, epidemiologic connection to enteroviruses originated from China. However, since May, 2013 there has been detected a boost activation of epidemic process as regards enteroviral infection, followed by the formation of two major foci with clustered infection, due to importation from Thailand as well. Emergency situation under conditions of flood (August-September, 2013) has contributed to aggravation of epidemiological situation on enteroviral infection. It has led to the increase in numbers of the exposed up to the maximum level for the past few years. In the territory of the temporal accommodation sites, where affected by high water and exposed to the infection population was placed, registered have been the cases of clustered enterovirus infection

Multiannual Analysis of Epidemiological Process Manifestations as Regards Enteroviral Infection in the Khabarovsk Territory, and the Key Factors that Predetermine Aggravation of Epidemiological Situation under the Terms of Flood

Carried out has been retrospective analysis of epidemiological process manifestations as regards enteroviral infection in the Khabarovsk Region over the period of 7 years, prior to rainfall floods in 2013. Revealed is the possibility of aggravation of epidemiological situation during hydrological emergency situation. The premises are as follows: persistent due to specific climate conditions prevalent in the Khabarovsk Territory (high air and surface water temperatures, and high humidity rates) unfavorable epidemiological situation on enteroviral infections, virus-carriage in “healthy” people and extensive dissemination of enteroviruses in the water bodies of ambient environment. Moreover, widespread circulation of different enterovirus genotypes, including the isolates with high genetic similarity to the strains identified earlier in the adjoining People’s Republic of China, takes place

Epidemiological Features of Enterovirus Infection during Flood on the Territory of Jewish Autonomous Region

Long-term manifestations of epidemiological process of enterovirus infection in the Jewish Autonomous Region were similar to those in the Khabarovsk Territory, though with a lower intensity. After establishment of emergency situation regime, in view of the rainfall flooding in 2013, enterovirus morbidity rate had been increasing within three weeks duration, then started to fall rapidly. Clustered cases of enterovirus infection were not registered. Viral serous meningitis ratio was insignificant as minor forms of the disease prevailed; coxsackie virus A-9 and echovirus-6 dominated. During the flood period isolated from samples of patients with minor forms of enteroviral disease were three enterovirus strains, type 71, sub-genotype C4a, possessing a high degree of genetic similarity to the Chinese ones, 2010-2011. All in all impact of the natural disaster on the epidemiological situation on enteroviral infection in the Jewish Autonomous Region turned to be insignificant

Epidemiological Characteristics of Enterovirus Infection in the Khabarovsk Territory under Hydrologic Emergency Situation

The paper contains the data on the role of high waters (2013) in changing epidemiological situation on enterovirus infections in the Khabarovsk Territory. The incidence rate in the region was characterized by the significant increase even before the flood, 2013. Thus, two peaks of enterovirus morbidity curve were identified for the period of a week: one - more intensive, another - coincident with flood outbreak. Enterovirus epidemiological process was notified by the changes in clinical picture among the infected population and cohort age-related structure. The percentage of the patients with enterovirus infections in the foci clusters and the index of people infected due to possible exposure to shattering impact of the flood, turned out to be low. However, revealed was high rate of heterogeneity of the circulating enterovirus strains, non-specific for the Khabarovsk territory and mostly originating from countries of Asia-Pacific region - coxsackie A viruses, which might stand for a possible cause of unfavorable epidemiological situation in 2013