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How Influenza A Virus Causes ‘‘Epidemics’’ and ‘‘Pandemics’’ among the Populations?

Sleman SS

Influenza is a major cause of sickness and death around the world and is one of the most important infectious diseases confronting the world today. Influenza A virus is the leading cause of seasonal epidemic and pandemic flu globally. Both epidemic and pandemic flu are found to be associated with the high morbidity and mortality rates worldwide, but that pandemic is thought to have accounted for about 50 million or more deaths and is obviously a matter of great concern, can cause a severe, easily transmissible disease among the community and everyone at risk of infection. The purpose of this study is to describe the mechanisms by which the influenza A viruses can cause epidemic and pandemic flu worldwide. In conclusion the extensive infection is mainly because the influenza A virus, like other RNA viruses, has capability to undergo a continuous antigenic variation either via a point mutation causing gradual change in the shape of the HA surface antigens known as ''Antigenic drift'' and it is found to be responsible for seasonal epidemics or through a genetic reassortment that leads to a major change in the surface antigens known as ''Antigenic shift'' and generation of entirely novel strains among the population with no pre-existing immunity as a result sporadic pandemics will occur.