Abstract
Relevance. Influenza is characterized by global distribution and the difference in its seasonality in countries with temperate and tropical climates. The importance of studying antigenic variation of influenza viruses due to the fact that changes in the antigenic structure is an evolutionary mechanism of adaptation of the virus to ensure its survival and cause annual epidemics.Aims. The Aim of this study was to identify the peculiarities of the geographical spread of influenza (seasonal), etiology and the rate of antigenic variability of influenza viruses A and B.Materials and methods. Based on data from WHO Reference research centers, information was collected on circulating influenza virus strains from 1975 A(H3N2), 1977 A(H1N1)pdm09 and type B of the Yamagata and Victoria lines from 1987 to 2019, as well as data on the number of all identified influenza viruses and individual strains circulating in the Northern and Southern hemispheres from 2008 to 2018.Results and discussion. Analysis of the global spread of influenza, its etiology and antigenic variability of viruses, according to WHO, showed that the influenza A(H1N1)pdm09 virus was the main causative agent of epidemics and regional outbreaks in seasons of high influenza activity in all countries except the United States and Canada, where influenza A(H3N2) and B viruses dominated in countries with severe seasonality, the change of season led to a change in the etiology of influenza, and in tropical countries, the A(H1N1)pdm09 virus more often remained dominant in all seasons of the year.Conclusions. The pronounced seasonality of influenza in Northern countries and its absence in tropical countries, where regional outbreaks prevailed in all seasons of the year, were confirmed. Low antigenic variability of influenza A(H1N1)pdm09 strains was confirmed, and the highest – A(H3N2). Among influenza B strains in the Victoria line had less antigenic variability, because the duration of its circulation before the appearance of a new drift variant was longer than that of the Yamagata line. The tendency to increase the total duration of circulation of influenza viruses B/Victoria, A(H1N1)pdm09 and B/Yamagata due to increased circulation before the emergence of new drift variants is shown.
Highlights
The importance of studying antigenic variation of influenza viruses due to the fact that changes in the antigenic structure is an evolutionary mechanism of adaptation of the virus to ensure its survival and cause annual epidemics
The Aim of this study was to identify the peculiarities of the geographical spread of influenza, etiology and the rate of antigenic variability of influenza viruses A and B
Based on data from WHO Reference research centers, information was collected on circulating influenza virus strains from 1975 A(H3N2), 1977 A(H1N1)pdm09 and type B of the Yamagata and Victoria lines from 1987 to 2019, as well as data on the number of all identified influenza viruses and individual strains circulating in the Northern and Southern hemispheres from 2008 to 2018
Summary
Особенности эпидемического процесса при гриппе и его этиологии в странах Северного и Южного полушарий в период циркуляции пандемического вируса А(H1N1)pdm (по данным ВОЗ). Для гриппа характерно глобальное распространение и различие его сезонности в странах с умеренным и тропическим климатом. Его этиологии и антигенной изменчивости вирусов, по данным ВОЗ, показал, что вирус гриппа А(H1N1)pdm был основным возбудителем эпидемий и региональных вспышек в сезоны высокой активности гриппа во всех странах, кроме США и Канады, где доминировали вирусы гриппа А(H3N2) и B. For citation: Karpova LS, Pelikh MYu, Popovtseva NM et al Features of Epidemic Process of Influenza and its Etiology in the Countries of the Northern and Southern Hemispheres in the Period of Circulation of Pandemic Virus A(H1N1)pdm (According to WHO). Материалы и методы В качестве источников информации об уровнях географического распространения заболеваний гриппом и о циркулирующих вирусах гриппа в странах Северного и Южного полушарий использовали сайты FluNet WHO, Европы (FluNewsEurope), Канады (FluWatch), США (CDC), Ю. Number of years with high and low geographical distribution in the seasons of high and low influenza activity from 2009 to 2019 seasons influenza achvity высокой high low Высокий
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