Swine flu
Swine influenza is an infection caused by any one of several types of swine influenza viruses. Swine influenza virus (SIV) or swine-origin influenza virus (S-OIV) is any strain of the influenza family of viruses that is endemic in pigs.[2] As of 2009, the known SIV strains include influenza C and the subtypes of influenza A known as H1N1, H1N2, H2N1, H3N1, H3N2, and H2N3.
Swine influenza virus is common throughout pig populations worldwide. Transmission of the virus from pigs to humans is not common and does not always lead to human flu, often resulting only in the production of antibodies in the blood. If transmission does cause human flu, it is called zoonotic swine flu. People with regular exposure to pigs are at increased risk of swine flu infection.
Around the mid-20th century, identification of influenza subtypes became possible, allowing accurate diagnosis of transmission to humans. Since then, only 50 such transmissions have been confirmed. These strains of swine flu rarely pass from human to human. Symptoms of zoonotic swine flu in humans are similar to those of influenza and of influenza-like illness in general, namely chills, fever, sore throat, muscle pains, severe headache, coughing, weakness, shortness of breath, and general discomfort.
It is estimated that in the 2009 flu pandemic 11–21% of the then global population (of about 6.8 billion), or around 700 million to 1.4 billion people, contracted the illness—more in absolute terms than the Spanish flu pandemic. Actual fatalities ranged between 12,000 and 18,000. However, in a 2012 study, the CDC estimated more than 284,000 possible fatalities worldwide, with range from 150,000 to 575,000. In August 2010, the World Health Organization declared the swine flu pandemic officially over
Subsequent cases of swine flu were reported in India in 2015, with over 31,156 positive test cases and 1,841 deaths up to March 2015.
In pigs, a swine influenza infection produces fever, lethargy, sneezing, coughing, difficulty breathing and decreased appetite. In some cases the infection can cause miscarriage. Although mortality is usually low (around 1–4%),[2] the virus can produce weight loss and poor growth, causing economic loss to farmers. Infected pigs can lose up to 12 pounds of body weight over a three- to four-week period. Swine have receptors to which both avian and mammalian influenza viruses are able to bind to, which leads to the virus being able to evolve and mutate into different forms. Influenza A is responsible for infecting swine, and was first identified in the summer of 1918. Pigs have often been seen as "mixing vessels", which help to change and evolve strains of disease that are then passed on to other mammals, such as humans.
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