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\f0\fs24 \cf0 Timeline of human flu-strain infections\
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The European avian flu outbreak is caused by a H5N8 subtype of the Influenza Type A virus. Subtypes are categorised by two proteins on the virus's surface \'96 haemagglutinin (HA) and neuraminidase (NA)\
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1918-19: Spanish flu pandemic kills 20-50 million people worldwide\
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Influenza Type A\
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Neuraminidase: Mushroom-shaped spikes of GP act as enzyme to break down sialic acids and penetrate mucous membrane of respiratory tract\
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10 subtypes of NA \'96 N1, N2,N3, N7 and N9 infect humans \
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Lipid envelope: Outer membrane supports around 500 spikes of HA and NA proteins\
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M1 matrix:Protein shell gives strength and rigidity\
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Nucleocapsid: Eight segments of single-stranded RNA \'96 genetic material of virus\
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M2 ion channel: Allows acids to enter virus\
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Haemagglutinin: Rod-shaped spikes of glycoprotein (GP)responsible for viral penetration into host cell\
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17 subtypes of HA \'96 H1, H2, H3, H5, H7, H9 and H10 infect humans\
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H2N2 1957-58: Asian flu originates in China and spreads globally, killing 1.5 million people\
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H3N2 1968-69: Hong Kong flu pandemic of \'93variant\'94 of H2N2 kills up to 750,000 people worldwide\
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H5N1 1997: First time an influenza virus is found to be transmitted directly from birds to people. 18 people infected in Hong Kong \'96 six fatalities\
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H9N2 1999: New bird flu strain appears in humans \'96 no fatalities\
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H7N2 2002: Infection found in one person in U.S. following poultry outbreak\
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H7N7 2003: New bird flu strain infects 89 people in Netherlands \'96 one fatality\
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H7N3 2004: New strain detected in humans \'96 two poultry workers in Canada\
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2004: New strain detected in humans \'96 two poultry workers in Canada\
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H10N7 2004:New bird flu strain detected in humans \'96 two infants in Egypt\
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H5N1 2007: 88 cases in Southeast Asia and Nigeria, 59 fatalities reported\
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H1N1 2009: Swine flu pandemic spreads to more than 70 countries, killing 23,500 people, 12,500 in U.S.\
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H7N9 2013: New avian flu crosses to humans. 443 cases in China, Hong Kong, Taiwan and Malaysia \'96 unofficial death toll of 127\
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Sources: CDC, ECDC, NIAID, News-Medical.Net\
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Picture: CDC\
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