In an analysis of the severity of the last pandemic brought about by the Influenza A(H1N1)pdm09 variant, according to the survey carried out by the WHO, around 150,000 deaths were registered on the planet until the 1st of April 2010. Samples from previous pandemics, such as Spanish flu, English flu, Hong Kong flu, and the Influenza A(H1N1)pdm09 virus, originated from shift-type mutations that occur by viral genome segments recombination of viral samples from different animal origins 10. ![]() The H3N2 strain recreated, in 1968, the same scenario with the Hong Kong flu 8 and, finally, in 2009, the A(H1N1)pdm09 strain, of swine-origin, had its first cases notified in Mexico, being disseminated, soon after, throughout the European continent and Oceania 9. In 1957, a new strain of Influenza (H2N2) caused epidemic outbreaks in several regions of the globe, becoming known as Asian flu 7. In later years, the constant remodeling and antigenic mutability of the virus brought about new pandemic scenarios. Because it has animal reservoirs and has high virulence in humans, this subtype and its mutations still affect the population today 1, 4.īetween 19, Influenza A (H1N1), of avian origin, became responsible for the so-called Spanish flu, commonly cited as "the greatest medical holocaust in history", with millions of deaths worldwide 5, 6. In the A H1N1 virus, antigenic subtype 1 of structure H and antigenic subtype 1 of structure N are present. Viruses of the genus Alphaorthomyxovirus (genus A) are classified according to the antigenic subtype of two surface structures, hemagglutinin (H, 19 subtypes) and neuraminidase (N, 11 subtypes), responsible for the processes of viral adsorption and cell receptor cleavage, respectively. The genera A and B cause higher mortality however, only genus A has pandemic potential. Three virus genera (A, B, and C) involved in respiratory conditions belong to this family. ![]() According to the World Health Organization (WHO), the term pandemic refers to a state caused by the emergence and dissemination of a new pathogen, with the ability to trigger a disease, often severe, with significant ease, by its replication and transmissibility between humans 2, 3.Īmong the pandemics that have plagued humanity in the last 100 years, those caused by influenza viruses belonging to the Orthomyxoviridae family stand out. ![]() With the advancement of epidemiology and understanding of infectious diseases, social relations, demography, and mobility resulting from the globalization process are increasingly becoming protagonists in the dissemination and transmissibility of microorganisms with the potential to be infectious in humans 1.
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