It has not yet been confirmed that the children have the H1N1 virus, only that they have flu-like symptoms. More than 60 million Americans developed infection from the novel H1N1 strain, an almost unbelievable number. In nearly all influenza cases were caused by the pandemic H1N1 virus, driving the previously dominant H3N2 underground.
New Word List Word List. So, while there are many combinations of H and N seen in birds, widespread human infection has only been caused by a few. H1N1, which was responsible for the pandemic virus and the recent swine flu pandemic, H2N2, the Asian flu pandemic strain, and the H3N2 Hong Kong pandemic strain in , which displaced the Asian flu.
The seasonal influenza A strains currently circulating in humans are H1N1 and H3N2, but they have changed a lot since their first introduction into humans. Influenza B strains do not circulate in animals, so they cannot cause a pandemic. But, like influenza A viruses, they continually change, so we will never become immune to every strain. These are the other component of the flu vaccine. When we are infected with a virus, or given an influenza vaccine the flu shot , we mount an immune response.
Antibodies against this virus will continue to circulate in our bodies, and will help prevent future infection with the same strain of virus if we are exposed to it again. But there are continual changes from year to year within each strain. This means that even if you were infected or vaccinated with the strains of flu circulating last year, when the virus comes around this year, it may have changed sufficiently so your antibodies no longer recognise it. So you can still get flu, even if you have been vaccinated.
While H5N1 and H7N9 strains can directly infect humans from birds, these viruses have not yet adapted sufficiently to spread from human to human. This happens if two different strains of influenza infect the one host.
They can swap and mix their genes, and may generate a virus that can now spread from human to human. It can take more than six months to make a vaccine against a virus with new combination of H and N types, so those of us who work on influenza hold our breath when there are reports of numerous people being infected with a new bird or animal strain. Who knows what numbers of the dice will be our next pandemic strain? Just like humans, pigs can get the flu.
However, we now know that the H1N1 flu virus is made up of genes from several different flu viruses that normally circulate among pigs, birds, and humans. This strain was the most common cause of influenza in , when it caused disease worldwide "pandemic". H1N1 flu is caused by an influenza A virus.
The letters H and N in the subtype name stand for proteins found on the surface of the virus, which are used to distinguish between different influenza A subtypes. Influenza viruses are constantly changing their genes, a process called mutation. When a swine flu virus is found in humans, it is said to have "jumped the species barrier. Because humans have no natural protection or immunity to the virus, they are likely to become ill. The H1N1 flu virus is made up of genes from flu viruses that normally cause influenza in pigs, birds, and humans.
H1N1 flu virus is contagious. Person-to-person transmission of H1N1 flu virus occurs, and the virus is easily spread among people. It is believed that it is spread the same way as regular seasonal influenza. A person infected with H1N1 flu virus can infect others starting 1 day before symptoms develop and up to 7 or more days after becoming ill. Coughing and sneezing release the germs into the air, where they can be breathed in by others.
The virus can also rest on hard surfaces like doorknobs, ATM buttons, and counters.
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