Influenza viruses

The history of influenza viruses teaches that influenza originates from volatile, generically aquatic animals, and then passes to man through the "jump" in pigs. The promiscuity of the farms, as it is used in Asia, determines this passage and then the spread. This gave rise to the Spanish flu (1918, H1N1), the Asian flu (1957, H2N2), that of Hong Kong (1968, H3N2) and so on. The strains spread in some years may also present relationships with those of other years. The swine origin influenza virus (S-OIV) detected in April 2009 in Mexico, Canada and USA exibthed an unique genome composition not shown before. According to the flu vaccinations compaign influenza vaccine is produced before the start of the flu season, which means that the virus almost never coincided with does tested early to produce the vaccine. The main componet of the viral family for human pathology was the agent of the small pox, the first disease to be eraticated by a vaccine.