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H1N1 Appears To Be Transmittable From Human To Pig
mpetch writes "In an interesting twist, it appears that H1N1 influenza can be transmitted from humans to swine. Apparently a Canadian pig farmer vacationed in Mexico, returned to Canada and infected about 10% of the swine on an Alberta farm. The swine subsequently developed flu symptoms."
Influenza viruses go back and forth between humans, pigs, and birds, and they also mutate regularly. So, this didn't really "start" anywhere, it's a normal part of how the influenza virus lives.
From WHO: "There is no indication of virus adaptation through transfer from human to pigs at this time."
http://www.who.int/csr/don/2009_05_03a/en/index.html
US exports $5 billion+ pork each year. Mexico imports most of its pork from US/Canada. Other countries such as China know that the swine flu was much more likely to have incubated in the massive pig farms of US and Canada before transferring to humans, rather than the other way round as so called "news" like this try to make us believe.
"China was also selective, banning only pork from Texas, California and Kansas, while the Philippines, South Korea, Thailand, Kazakhstan, Serbia, Ukraine, United Arab Emirates and Ecuador said theyâ(TM)re stopping all U.S. pork imports, according to Nefeterius Akeli McPherson of the U.S. trade representativeâ(TM)s office."
China ban US pork
Current reports indicate that this strain of H1N1 influenza contains genetic material from swine, avian, and human forms of the disease. That's probably why it can spread easily from humans to pigs; normally, a virus does not cross species unless there is frequent or prolonged close contact between the two, because making the leap depends on genetic mutation. In this case, the virus is already adapted to both hosts.
To further clarify, the name "H1N1" refers only to a particular configuration of two proteins on the surface of the virus (H is hemagglutinin and N is neuraminidase). The configuration of these proteins determines how the immune system will react to a given strain of influenza (i.e. which antibodies will be able to recognize and attack it), which is the most useful information to have when it comes to treating the disease, but there are other factors that determine a given strain's properties.
So the news here is not that H1N1 flu can jump from humans to pigs -- it can't, not necessarily -- the news is that this variety appears to be able to. And it's not that we didn't know this could be possible -- we've seen this kind of thing countless times, and in fact it's believed that all forms of influenza ultimately come from birds -- it's just that calling it "H1N1 flu" doesn't give us enough information to make those kinds of predictions about its virulence.
Breakfast served all day!
He's still right. What you're saying is basically akin to saying that the air in a car is "recycled" because it's not moving 100% of the air mass at all times. For a good duration of the time you spend in a car with closed windows, you're breathing in the same air you breathed out a moment ago. But it isn't airtight, and there are vents, so 100% of it gets cycled out eventually.
When people speak of "recycled air" on an airplane they seem to think that aircraft are like submarines, completely airtight, and the only air is that which you had when you took off from the runway. This simply isn't the case -- it's all going to get cycled out and continuously refreshed. Of course a certain amount is getting recirculated, just as in a closed car, but sooner or later it's all fresh air. You're not landing with the same air molecules you had when you took off.
In commercial aircraft (I don't know about small craft like Cessnas), there are one or more apertures, usually near the rear of the plane, which can open and close to variable diameters, and that's part of how cabin pressure is regulated. You pump more air into the cabin than you let out through the aperture, and the result is a higher air pressure than what's outside -- and that air is indeed being pumped in from the outside, through the engines (which are basically doing nothing but forcing air around at high velocity anyway).
Incidentally this is also why shooting a gun in an aircraft and blowing a hole through the hull isn't the huge deal everyone thinks it is, resulting in decompression and a big crisis. If such a thing occured, the apertures would simply close a bit more to compensate for the drop in pressure, and all would be well -- at least as far as cabin pressure is concerned.
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