How Actually the Influenza Pandemics Occur

 

Pandemics or Global epidemics of influenza have occurred for hundreds of years. There were three pandemics during the 20th century. They occurred in 1918 1957 and 1968. The 1918 pandemic took the largest toll causing an estimated 50 million deaths worldwide the first pandemic of the 21st century began in 2009. But how does a pandemic occur influenza A viruses very slightly. 

Year-to-year a phenomenon called antigenic Drift these small variations are the reason why the vaccine must be updated every flu season influenza A viruses also can undergo dramatic genetic changes called antigenic shift that may cause a new influenza strain to which we have little to no immunity. 

If this strain spreads easily among people it may cause a pandemic the immune system targets to proteins on the surface of influenza A viruses. Has hemagglutinin and neuraminidase hemagglutinin has 16 confirmed subtypes of proteins neuraminidase has nine from these protein combinations scientists named influenza viruses, for example, an h5n1 virus contains hemagglutinin subtype 5 and neuraminidase subtype 1 Antigenic shift can occur when two different influenza A viruses circulating in the environment in fact and multiply inside the same cell while inside the cell these parent viruses can exchange or Rio sort genetic material and create a new virus through reassortment of the eight Gene segments of each virus. There are theoretically 256 possible virus combinations. 

Pandemic viruses also can emerge in other ways among these is adaptation scientists believe that the 2009 H1N1 virus was the product of two influenza A viruses that were circulating in pigs. The viruses are thought to have resorted and adapted to create a new virus capable of infecting people. If an emerging virus transmitted sufficiently from person to person it would be a challenge for scientists to produce an effective vaccine fast enough to limit its prey. That is particularly true with the amount of international travel that occurs today in a matter of hours one person infected with a new form of influenza can spread the virus to people in another part of the world. 

The National Institute of allergy and infectious diseases and other research institutions around the globe are working to find better ways to prevent diagnose and treat pandemic influenza these efforts include testing new drug and vaccine Concepts studying flu viruses and animals and humans and documenting factors that could lead to the emergence of strains with pandemic potential the aims of these projects are to help health officials quickly detect and emerging influenza A virus. 

And Implement measures that bring the outbreak under control. 

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