Three Main Categories of Flu Virus

Three Main Categories of Flu Virus

Since April 2009, the new influenza A (H1N1) virus has spread across the United States indicating sustained human-to-human transmission with momentous infection rates. Information to date suggests that most cases of illness from this virus are parallel in severity to seasonal influenza.
Influenza is a contagious respiratory illness caused by a virus. Flu viruses are divided into three main categories. Type A, found in animals and humans and has been associated with all previous pandemics; Type B, found only in humans which causes seasonal flu; and Type C, which again is found only in humans however only causes mild illness.
Swine influenza (referred to H1N1 virus) refers to the type of influenza caused by any strain of the influenza virus endemic in pigs, also referred to as swine. The strains endemic in swine are called swine influenza virus (SIV). Swine flu is common in swine (pigs) and rare in humans. Rarely, SIV mutates into a form that is able to be passed easily from human to human. The current strain (H1N1) responsible for the current swine flu outbreak is a Type A flu virus that is believed to have undergone such a mutation.
The first news reports of the H1N1 come from Mexico on April 23rd, 2009, reports stated that a new virus had emerged which causes significant illness and is easily transmitted from person to person. In late March and early April 2009, cases of human infection with the H1N1 were reported in Southern California and near San Antonio, Texas. Other U.S. states have reported cases of the H1N1 virus in humans and cases have been reported internationally as well. Seven weeks later the WHO (World Health Organization) declared the H1N1 a pandemic; the first pandemic since 1967. A pandemic is an outbreak of an infectious disease that spreads across large regions ad potentially worldwide. By contrast, the term epidemic means a local outbreak of an infectious disease. In order for a pandemic to occur a new flu virus must emerge, the human...

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