🚀 go-pugleaf

	I'm not the most qualified person to answer this, but I'll try...

franklin@ug.cs.dal.ca (Steve Franklin) writes:
> 
> Quick question for you,
> 
>    In light of Bouchard's problem with the streptococcal bacteria, I was
> wondering about the following theory I've had:
> 
> Perhaps this usually 'peaceful' bacteria can undergo such hyper-accelerated
> selection that it becomes incredibly strong and resistant to anti-biotics,
> and at the same time, it's nature changes due to its very specific selection
> criteria? 
	This sounds like what happened with the tuberculosis bacteria recently,
where a super-resistant strain turned up in the US (was it New York?) and was
killing people who contracted it, because none of the "standard" drugs worked
and it was more virulent as well.

> The question then would be - how come this super-strain doesn't spread all
> over and nuke us all in a giant plague? Well, it would seem possible to me
> that as the nature of the bacteria changes, so too would it's means of
> transmission. If the bacteria prefers to get into your bloodstream and
> tissue, rather than into your throat and lungs, then transmission of the
> bacteria becomes more difficult - they lose their airborne advantage, and
> require transmission via open wounds. 
	Hmm...good question...HIV is very virulent, but it also requires 
some exchange of body fluids to pass from one host to another.  Is it 
possible that the more virulent a bacteria gets, the more "delicate" it
gets with regards to transmission?  Seems not completely unlikely to me,
but I am not a virologist/bacteriologist....

Jennifer
******************************************************************************
* Jennifer A. Hoar          _____       If the Creator had indeed lavished   *
* Biology Dept	           /     \      his best design on the creature he   *
* Dalhousie University 	   | 0 0 |               created in his own image,   *
* Halifax, NS B3H 4J1 __   \  o  /   _____/      creationists would surely   *
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#Nice speculation about the functional reason:#

franklin@ug.cs.dal.ca (Steve Franklin) writes:

>The question then would be - how come this super-strain doesn't spread all
>over and nuke us all in a giant plague? Well, it would seem possible to me
>that as the nature of the bacteria changes, so too would it's means of
>transmission. If the bacteria prefers to get into your bloodstream and
>tissue, rather than into your throat and lungs, then transmission of the
>bacteria becomes more difficult - they lose their airborne advantage, and
>require transmission via open wounds. 

If the pathogen can only reach its goal (survival, reproduction,
spreading> by killing its host, selective pressure to become more
virulent will be on it. It may (mustn't> than eventually extict itself
with a hyper-sensitive host. But if it can spread from one living host
to the next, coevolution may lead to a more avirulent pathogen and a
more tolerant host. There is one example, where the avirulent
vaccine-strain has spread on the cost of the virulent form, but I
don't know the english name for it <`Pocken' in german>.

#Here comes a speculation about the historical reason:# 
  
Assuming this type of coevolution happened to streptococcal bacteria,
the virulent form might be a kind of atavism, or the relict of the
virulent strain. 

P.S.: I want to thank, though I did it already via e-mail, Peter W.
Pappas for his answer, officially.