Epidemiology

In grippeenza is spread from person to person by expectorates and sneezes, exclusively the virus doesnt begin its journey in a gentle host. Instead, wild aquatic birds such as ducks and shore birds perpetuate 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 can migrate thousands of miles, the swell birds can spread the virus across the globe notwithstanding before the microbe makes contact with the human population.

As it happens, the puddle of the virus found in wild birds doesnt replicate well in human beings, and so it must first flow to an intermediate host--usually domestic fowl or swine--that drinks water dirty by the feces of aquatic birds. Horses, whales, seals and mink are similarly periodically infected with influenza. Although the intermediate hosts can sicken and split from the infection, swine can live long enough to serve 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 important lineament in the history of the human disease.



These animals appear to serve as living laboratories where the avian and mammalian influenza viruses can come together and share their genes (a reassortment of RNA segments) and create new 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 obnubilate that is rich in virus particles. Most pandemics originate in China, where birds, pigs and people live in close proximity. Hong Kongs 1997 bird flu was an avian influenza virus that probably attained 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 full essay, suppose it on our website: Ordercustompaper.com



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