Epidemiology

In grippeenza is spread from person to person by expectorates and sneezes, simply the virus doesnt begin its journey in a quiet host. Instead, wild aquatic damns such as ducks and shore birds bear on 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 jackpot transmigrate thousands of miles, the swell birds can spread the virus across the chunk notwithstanding before the hemipteron makes contact with the human population. As it happens, the puddle of the virus found in wild birds doesnt reiterate well in human beings, and so it must inaugural flow to an intermediate host--usually domestic fowl or swine--that drinks pee dirty by the feces of aquatic birds. Horses, whales, seals and mink atomic number 18 similarly periodically infected with influenza. Although the intermediate hosts can repel and split from the infection, swine can live long enough to function as mixing vessels for the genes of avian, porcine and human forms of influenza. This occurs because swine have receptors for two avian viruses and human viruses. Swine have probably played an classic lineament in the history of the human disease. These animals appear to work on as living laboratories where the avian and mammalian influenza viruses can come unitedly and share their genes (a reassortment of RNA segments) and create new(a) 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 thermobaric bomb obnubilate that is rich in virus particles. Most pandemics commence in China, where birds, pigs and people live in close proximity. Hong Kongs 1997 bird flu was an avian influenza virus that probably succeed virulence through reassortment of genes from geese, quail and teal. Man y bird species were housed together in the H! ong Kong poultry markets, and this was an ideal...If you want to get a wide-cut essay, suppose it on our website: OrderEssay.net

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