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There have been several over the decades. The first one found was the one that pigs get (hence the name), H1N1, in the1930's. Then when people started being able to catch that one or mutations of that one, there is speculation that there could have been several others in retrospect, including the "Spanish Flu" that started the influenza pandemic in 1918, but there are no longer samples to test that hypothesis. Then there was the 1976 Swine Flu (see more in related questions), and now most recently, the H1N1/09 swine flu, the one that caused the 2009 pandemic and still circulating and making people ill today.
See the related questions below, about when swine flu started and what caused the 2009 swine flu to develop, for more details.
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∙ 12y ago
Wiki User
∙ 13y agothere are three known subtypes of human flu virus A: H1N1, H1N2, and H3N2. Avian viruses can infect pigs, but people are generally not affected. That changed when there was an outbreak of H5N1 in Hong Kong in 1997.
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∙ 10y agoThe influenza virus, commonly known as the flu, comes in approximately 25 separate strains. There are 16 proteins known as HA, which is known scientifically as hemagglutinin, and nine strains of NA protein, known scientifically as neuraminidase.
Wiki User
∙ 13y agoThere are 16 HA subtypes and nine NA subtypes of influenza A virus.
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How many Influenza A subtypes can infect birds?
There are 15 different Influenza A subtypes that can infect birds
What organism does the influenza infect?
Humans are organisms which can become infected by the influenza virus.
How many types of the Influenza Viruses are there?
According to the United States Center for Disease Control and Prevention, there are 4 types of Influenza viruses, but only three infect humans (A, B & C). Influenza D infects cattle and is not known to infect people.
How many types are there of influenza viruses?
According to the United States Center for Disease Control and Prevention, there are 4 types of Influenza viruses, but only three infect humans (A, B & C). Influenza D infects cattle and is not known to infect people.
Where does influenza circulate when it is not infecting humans?
Can't It hide away in your cells for a while before it decides to infect you?
Does influenza A virus infect turtles?
No. Most viruses target certain cells. In the case of influenza A, some mammals (including humans) and some birds have been infected.
Are all influenza Type A viruses the Swine Flu?
No, the pandemic A-H1N1/09 "swine flu" is just one of many Type A influenza strains. It is also one of many H1N1 flu subtypes. Besides Type A influenzas, there are also influenza Types B and C in humans.
What is the difference between Flu A and Flu B?
They are caused by two different kinds of viruses. There are three types of influenza viruses that have been classified according to the types of proteins they have. There are Type A, Type B, and Type C influenza viruses. Type A and B each have many different strains. Type C does not.Type A influenza is one of the more common types we see in the seasonal flu among humans and it is also a very common type that many other animals get. It has subtypes and strains that differ, which is why having one subtype will not give you immunity from all the other subtypes and strains.Type B influenza is also a common type among humans and is found only in humans. It is not divided into subtypes but there are multiple strains.Type C has been found in humans, pigs, and dogs. The symptoms are usually very mild, milder than those of Type A and B influenza viruses, and it typically doesn't cause epidemics. It is not divided into different subtypes or strains.
What viruses can infect your airway?
Three that come to mind are adenovirus, influenza, and RSV.
How fast rabies infect humans?
Rabies infect humans depending on how far is the bite to your brain.
Why does influenza have RNA?
Influenza has RNA because it steals DNA/RNA from host cells. Proteins also help infect the DNA/RNA.
What are the organisms that the Swine Flu virus can infect?
A swine influenza virus (SIV) is called that because it comes from a virus family that is endemic in pigs. The H1N1 influenza virus has other subtypes and strains besides the 2009 pandemic (H1N1/09) "swine flu". Different subtypes can infect different organisms. However, they all infect animals (mammals and birds), and not plants or bacteria.The original H1N1 virus is thought to have infected birds first. It then mutated to pigs kept in very close areas with birds/fowl (probably in Asia). The subtype currently commonly called swine flu or pig flu (a type of H1N1) mostly infects pigs today, and infected only birds and pigs at first. Then it mutated to strains that also infect humans (then called a triple reassortant/reassortment because it contained genetic material from birds, pigs, and humans).From the mutation that allowed humans to be infected, it is believed that all other versions of influenza that can cause pandemics in humans have developed. The new subtype that caused the 2009 pandemic swine flu (H1N1/09) was the newest of those, discovered first in Mexico in 2009 (see the related question below for much more information on the process that caused the H1N1/09 subtype development). That version was a quadruple reassortant, containing genetic material from four sources: birds (bird flu/avian influenza), pigs (two types of swine influenza from pigs-European swine flu and Asian swine flu) and humans.The strains of H1N1/09, the subtype causing the 2009 pandemic swine flu, have been been identified as the flu pathogen in infected pigs, humans, dogs, cats, ferrets, fowl and other birds, and one cheetah.
