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

Seroepidemiology and molecular epidemiology of enterovirus 71 in Russia.

Enterovirus 71 (EV71) is an emerging human pathogen causing massive epidemics of hand, foot and mouth disease with severe neurological complications in Asia. EV71 also circulates in Europe, however it does not cause large outbreaks. The reason for distinct epidemiological patterns of EV71 infection in Europe and Asia and the risk of EV71 epidemic in Europe and Russia remain unknown. Seroepidemiology of EV71 and molecular epidemiology of occasional EV71 isolates were studied to explore circulation of EV71 in Russia. In six regions of Russian Federation, seroprevalence of EV71 in sera collected in 2008 ranged from 5% to 20% in children aged 1-2 years and from 19% to 83% in children aged 3-5 years. The seroprevalence among elder children was significantly higher (41-83% vs. 19-27%) in Asian regions of Russia. EV71 strains identified in Russia in 2001-2011 belonged to subtypes C1 and C2, while genotype C4 that was causing epidemics in Asia since 1998 emerged in 2009 and became dominant in 2013

Characteristics of Nasopharyngeal Carriage of Bacterial Pathogens in Children and Adults Suffering from Recurrent Respiratory Infections in Khabarovsk City in 2015–2018

Objective. To designate the nasopharyngeal carriage of bacterial pathogens among children and adults diagnosed with recurrent respiratory diseases residing in the Khabarovsk city during a four-year period.Materials and methods. Nasopharyngeal and oral swabs obtained from 7,043 children and adults were tested using classical bacteriological methods. In order to grow “difficult-to-culture” microorganisms a columbian agar with addition of 5% defibrinated sheep blood, incubation in the atmosphere rich with CO2 (5%), bacteriological analyzer Vitek 2 Compact were used. Real-time PCR was used to confirm the identification of S. pyogenes.Results. A high level of nasopharyngeal pathogens carriage (47%) was detected. The most prevalent microorganisms were as follows: S. pneumoniae (47%), M. catarrhalis (30.4%), H. influenzaе (17.5%), S. pyogenes (5.2%). The age groups at risk were children aged 0–6 years for S. pneumoniae and children aged 7–12 years for S. pyogenes. An emerging trend it the level of nasopharyngeal carriage of S. pneumoniae observed in 2018 was followed by the increase of registered incidence of pneumococcal pneumonia.Conclusion. Nasopharyngeal carriage of S. pneumoniae imposes a high risk of community-acquired pneumonia and other pneumococci-associated diseases, predominantly in children

Phylogenetic tree of EV71 isolates from Russia and CIS (indicated in bold) and all GenBank sequences of EV71 genotype C that differ by over 1%.

<p>For Russian/CIS sequences, the isolate number is indicated, which refers to the sampling location indicated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0097404#pone-0097404-g001" target="_blank">Fig. 1</a>. The tree was created using the complete VP1 genome region (891 nucleotides) and the Bayesian Markov Chain Monte Carlo algorithm implemented in Beast 1.7.5. Scale bar indicates time. Branches are colored according to isolation region indicated in the legend.</p

Sampling territories (shaded on the map), the number of sampled sera, sociogeographic conditions in the study regions, prevalence and mean geometric titers of antibodies to EV71 in children aged 1–2 and 3–5 years.

<p>Social and economic status of the regions is provided according to the official census and statistical data. Climate zone is indicated in accordance with Köppen classification. Dfb, warm summer continental, even annual rainfall; Dfc, continental subarctic, even annual rainfall; Dwb, warm summer continental, low winter rainfall. Isolations sites of EV71 strains presented in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0097404#pone-0097404-g002" target="_blank">Fig. 2</a> are indicated with empty circles. Significance of Fisher's exact test comparing seroprevalence in younger and elder age groups is indicated above the bars of the seroprevalence graph; comparison regions are indicated by first letters. Only significant values are shown; * indicates p<0.05, ** p<0.01, *** p<0.001.</p

Vaccine Prophylaxis of Pneumococcal Infections in Children under Conditions of Severe Flood in the Amur River Basin

Background. Pneumococcal infection being one of the dominant causes of acute respiratory diseases and exacerbation of chronic ones is a serious problem for human health and society. The flood in the Amur river basin in the summer of 2013 created a special zone and risk conditions for the formation of respiratory pathology in the Far-Eastern region of Russia. We aimed to give clinical and epidemiological assessment of the effectiveness of vaccination programs of respiratory viral and pneumococcal infections and generalization of regional experience in the organization of a set of measures aimed at their prevention in the postflood period in the Far-Eastern region. Methods. The monitoring program includes children aged 2 to 5 years in the amount of 4988 with risk factors for pneumococcal infection. The pneumococcal conjugate vaccine Prevenar-13 was used for immunization. Data on the incidence of ARVI and pneumonia in children in pre- and postvaccination periods were to be recorded. The indicators and special criteria were used to assess the effectiveness of vaccination. To study the circulation of serovariants of pneumococcus in inflammatory diseases of the respiratory tract and nasopharyngeal carrier, bacteriological and molecular genetic methods (RT-PCR in the mode of multiprime detection) were used. Results. Differences in the frequency and range of serovariants of circulating isolates of pneumococcus in the postvaccinal period and in unvaccinated children, elimination of a number of serotypes, and appearance of circulation of nonvaccinated strains were revealed. The incidence of acute respiratory diseases and pneumonia among the vaccinated population for 2 years in the region decreased by 2.5 times. The coefficient of effectiveness of vaccination according to the indicator of morbidity of children with pneumonia reaches 75-100% with direct dependence on the age of children (r=0.98). Conclusion. Comparative statistical analysis revealed a high degree of effectiveness of regional programs with the methods of immunoprophylaxis of pneumococcal infections

Dynamic Changes in Hepatitis A Immunity in Regions with Different Vaccination Strategies and Different Vaccination Coverage

The data on hepatitis A virus (HAV) seroprevalence are critical for the implementation of a universal mass vaccination (UMV) strategy. The latter has not been implemented in Russia; however, regional child vaccination programs have been adopted in some parts of the country. The aim of this study is to assess changes in HAV immunity within the last decade in regions of Russia with different vaccination strategies and different vaccination coverage rates. In regions where UMV has not been implemented and HAV vaccination coverage rates do not exceed the national average, the 50% seroprevalence threshold has shifted in the Moscow region from people aged under 40 years in 2008 to people aged over 59 years in 2020, and from people aged under 30 years to people aged over 40 years in the Khabarovsk region. In two regions (Yakutia and Sverdlovsk), a two-dose-based UMV scheme has been in place since 2011 and 2003, respectively, and in Tuva single-dose child immunization was launched in 2012. These regional programs have resulted in a significant increase in HAV seroprevalence in children and adolescents. In Yakutia, 50% herd immunity had been achieved by 2020 in age groups under 20 years, compared to 20&ndash;30% seroprevalence rates in 2008. In the Sverdlovsk region, HAV immunity has increased to &gt;65% over the decade in children aged over 10 years, adolescents and young adults, whereas it declined in older age groups. However, a three-fold drop in HAV immunity has occurred in children under 10 years of age, reflecting a significant decline in vaccination coverage. In Tuva, HAV immunity rates in children under 10 years old increased two-fold to exceed 50% by 2020. These data suggest that UMV should be implemented on a national level. Measures to control vaccination coverage and catch-up vaccination campaigns are recommended in order to maintain the effectiveness of existing HAV vaccination programs