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Is it a myth that the bodies resistance to germs be built up by exposure?

by VonWeber
Tags: bodies, built up, exposure, germs, myth, resistance
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VonWeber
#1
Dec16-07, 03:19 PM
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I'm not sure is this is more a medical question, but I'm thinking it's more of something biologists would address?

When I see people criticized about eating things that have come into contact with unclean or doing other things that expose them to germs. I'll often hear people who know something about the immune system respond that they believe it's a good thing and it will build up or strengthen there immunity to be exposed to lots of germs. Its always sounded to me like a conclusion that they've reached on there own and weren't taught in school or such and It's not sounding very scientific. I've suspected for a while that this is just a myth... It seems to me it shouldn't really matter the quantity of germs you are exposed to as much as the variety. Being exposed to a variety would be a bad thing and immunity is irrelevant, as it seems to me, since if you happen to be exposed to the wrong germ it could be very harmful?
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DaveC426913
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Dec16-07, 03:51 PM
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"Bad" germs are opportunistic. If you keep yourself suurounded by "good" germs, then the bad ones are crowded out.

There has been a fad of antiseptic soaps going on for years, but the fad is dying as people realize that killing off "good" germs simply provides the opportunity for bad germs to gain a foothold.

Same thing with your immune system.
Moonbear
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Dec16-07, 03:56 PM
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It depends on the germ. There are beneficial bacteria that help with digestion that you'd want to keep around. There are harmful, highly virulent bacteria and viruses that even a low exposure would leave you very ill. And there are viruses that are closely enough related to nasty beasties that exposure to them will help you build up immunity to something much worse (i.e., exposure to cow pox won't make you sick and gives you immunity to smallpox). A large enough dose of anything will make you sick, but a low dose exposure could be easily fought off by a healthy immune system and provide better future protection (this is a similar principle through which vaccines work).

DaveC426913
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Dec16-07, 04:01 PM
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Is it a myth that the bodies resistance to germs be built up by exposure?

Quote Quote by Moonbear View Post
It depends on the germ. There are beneficial bacteria that help with digestion that you'd want to keep around. There are harmful, highly virulent bacteria and viruses that even a low exposure would leave you very ill. And there are viruses that are closely enough related to nasty beasties that exposure to them will help you build up immunity to something much worse (i.e., exposure to cow pox won't make you sick and gives you immunity to smallpox). A large enough dose of anything will make you sick, but a low dose exposure could be easily fought off by a healthy immune system and provide better future protection (this is a similar principle through which vaccines work).
Right, so the question is, what is "best practice" in terms of germs? Get rid of them or allow constant, low-level exposure?
Greg Bernhardt
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Dec16-07, 04:01 PM
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Quote Quote by Moonbear View Post
It depends on the germ. There are beneficial bacteria that help with digestion that you'd want to keep around.
There has been a trendy craze for yogurt with acidiphilous. Apparently, this germ if established in the digestive track, creates an acidic enviroment that many bad germs don't like.
Moonbear
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Dec16-07, 04:04 PM
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Quote Quote by Greg Bernhardt View Post
There has been a trendy craze for yogurt with acidiphilous. Apparently, this germ if established in the digestive track, creates an acidic enviroment that many bad germs don't like.
Mostly that's something you want available if you're taking antibiotics, since those kill all the "good" bacteria along with the bad in your digestive tract. For women, acidophilis is also protective against yeast infections...the same reasons DaveC mentioned, that both are naturally present, but normally, acidophilis keeps the proliferation of yeast to a minimum. Disrupting the balance allows the yeast to proliferate and become an infection.
chroot
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Dec16-07, 07:03 PM
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Recently, the public has decided that "germs are bad" and that people are supposed to be free of all microbial life, and live in environments free of all microbial life. Neither is possible, and both are short-sighted. Our bodies depend (very literally) on certain kinds of micro-organisms. Some theorize that the rise of asthma and allergies in modern cultures is caused, in part, by an increasing sterilization of our environments.

- Warren
Ivan Seeking
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Dec16-07, 07:18 PM
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A recent thread:

Antibacterial Soap No Better And May Be Worse Than Plain Soap
http://www.physicsforums.com/showthread.php?t=180787
DaveC426913
#9
Dec16-07, 07:38 PM
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Quote Quote by chroot View Post
Recently, the public has decided that "germs are bad"...
I'm not sure it's the public that have decided that.
Spirochete
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Dec16-07, 08:44 PM
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Quote Quote by DaveC426913 View Post
"Bad" germs are opportunistic. If you keep yourself suurounded by "good" germs, then the bad ones are crowded out.

There has been a fad of antiseptic soaps going on for years, but the fad is dying as people realize that killing off "good" germs simply provides the opportunity for bad germs to gain a foothold.

Same thing with your immune system.
http://aac.asm.org/cgi/content/full/48/8/2973

The bigger problem at this point is potential for generating cross resistance to other useful antibiotics, for example with multidrug efflux pumps. If you dig far enough into this study (in the full article in the discussion) it mentions that labaratory studies under "ideal" conditions have shown cross resistance to a few different antibiotics. It's just that we haven't seen it yet in bacteria isolated from people. But the mechanisms exist in a variety of bacteria.

If you have to disinfect your hands alcohol is better, the buggers don't become resistant to it for some reason.
VonWeber
#11
Dec19-07, 04:45 PM
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Quote Quote by Greg Bernhardt View Post
There has been a trendy craze for yogurt with acidiphilous. Apparently, this germ if established in the digestive track, creates an acidic enviroment that many bad germs don't like.
I've always been suspicious of the yogurt fad. The bacteria would have to survive until it reached the colon assuming the acidiphilous that thrive in milk are suited to live in the intestines.
DaveC426913
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Dec19-07, 08:42 PM
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Quote Quote by VonWeber View Post
I've always been suspicious of the yogurt fad. The bacteria would have to survive until it reached the colon assuming the acidiphilous that thrive in milk are suited to live in the intestines.
Milk/yogurt is high in fat. Fat resists digestion. It is possible to find fat that has made it all the way through the intestines and into the feces without disintegrating.
jim mcnamara
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Dec20-07, 08:47 AM
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I think the origin of this off-the-wall concept is the idea of a 'bored immune system'.
The bored immune system is an immune system that it not exposed to lots of foreign antigens, eg., from livestock, lots of different pets, etc. especially during adolesence.

Kids kept in very antigen free environment like the one in a modern high rise apartment building have limited exposure to these antigens. Kids on dairy farms have a lot of exposure. Farm children show low rates of asthma, children from the "antigen-deprived" environment show statistically higher rates of asthma.

So, this concept has now been misapplied to the germ theory of diesase: "Exposure to pathogens raises your resistance to them". The problem is, exposure to live pathogens does confer immunity if you do not die from the disease. Sensible innoculation depends on exposure to pathogens, yes, but the pathogens provide antigens with virtually no ability to cause disease.

In laymen's terms:
How many of you are willing to be exposed to live plague bacteria? Your chances of dying are maybe 5 in 10 or 50%. OR would you rather get a plague shot - one in 600000 chance of dying. The choice is yours.
DaveC426913
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Dec20-07, 09:09 AM
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Quote Quote by jim mcnamara View Post
In laymen's terms:
How many of you are willing to be exposed to live plague bacteria? Your chances of dying are maybe 5 in 10 or 50%. OR would you rather get a plague shot - one in 600000 chance of dying. The choice is yours.
Well, since this year, like previous years, I have chosen to forego the flu shot, I guess I'm in the former category.


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