Epidemiology

In grippeenza is spread from person to person by expectorates and sneezes, merely the virus doesnt begin its journey in a pleasing host. Instead, wild aquatic dames such as ducks and shore birds continue the influenza viruses that cause human pandemics. Although these birds carry the genes for influenza in their intestines, they usually dont be sum sick from the virus. And because they keep immigrate thousands of miles, the swell birds can spread the virus across the humankind notwithstanding before the hemipterous insect makes contact with the human population. As it happens, the puddle of the virus found in wild birds doesnt repeat well in human beings, and so it must basic flow to an intermediate host--usually domestic fowl or swine--that drinks piss dirty by the feces of aquatic birds. Horses, whales, seals and mink ar similarly periodically infected with influenza. Although the intermediate hosts can turn ones stomach and split from the infection, swin e can live long enough to coiffure as mixing vessels for the genes of avian, porcine and human forms of influenza. This occurs because swine have receptors for both avian viruses and human viruses. Swine have probably played an Copernican lineament in the history of the human disease.

These animals appear to advert as living laboratories where the avian and mammalian influenza viruses can come unitedly and share their genes (a reassortment of RNA segments) and create bleak strains of flu. When a strain of virus migrates into the human population, it changes into a disease-causing microbe that replicates in the respiratory tract. A sneeze or a cough spreads the virus in a contagious aerosol can obnubilate that is rich in viru! s particles. Most pandemics spring up in China, where birds, pigs and people live in close proximity. Hong Kongs 1997 bird flu was an avian influenza virus that probably accomplish virulence through reassortment of genes from geese, quail and teal. Many bird species were housed together in the Hong Kong poultry markets, and this was an ideal...If you want to get a beat essay, suppose it on our website: OrderEssay.net

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