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Polio vaccination

Chris Upton cupton at sol.uvic.ca
Thu Oct 20 12:13:11 EST 1994


In Article <mikep.222.000B9A10 at uniwa.uwa.edu.au>, mikep at uniwa.uwa.edu.au
(Michael Poidinger) wrote:
>In article <cupton.1132587280H at ra.uvic.ca> cupton at sol.uvic.ca ( Chris Upton)
>>I just read in our local newsaper "health column" that polio booster shots
>>were not being recommended since of the low prevalence of the disease in the
>>Western Hemisphere!!!
>>      Comments please!
>
>There are many difference between smallpox and 
>polio. The main point is that polio is a gut-tropic enterovirus, and hence is 
>passed out in faecal matter. The vaccine strains are live and infectious, 
>where the smallpox vaccine was not (infectious, that is. Nor was it smallpox 
>for that matter). It is thus very widespread and constantly circulating 
>throughout the community, especially in developing countries.  The WHO 
>proposal to erradicate the disease is aimed not at ablating the virus from the 
>world, but ensuring that the only poliovirus circulating is derived from 
>vaccine, ie no wt virus is still present.
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
How can this ever be attained when the vaccine strain mutates back to wt?
Although I believe this is usually with the mildest of the 3 strains.

So there's this huge pool of replicating polio virus (vaccine strain)
mutating as viruses like to do...........  (primarily in the 3rd world)
  
My point was really to ask what happens in the Western World as booster
shots are reduced and then people may be less willing to take the initial
vaccine + cost issues.....

Is there a big enough pool of polio replicating in the West to ensure that
there could be no polio epidemic in the rare situation that a mutated
vaccine virus finds a susceptible host?
These might be just VERY small risks.....  that's why I was asking :-)

- Maybe the boosters are just overkill and are not really required?????
- lots of questions here!!

>In addition, the poliovaccine strains are safe examples of a simple RNA virus, 
>as opposed to the incredible complexity and inherent danger of smallpox.  Many 
>labs around the world are investigating poliovirus to learn the nature of 
>viral replication, transmission etc, because the poliovirus is so well studied 
>and understood.  The use of vaccine strains in these studies means higher 
>levels of containment are not required.  Note that even at present, any 
>recombinant work with polio that may involving changing the virus 
>neurovirulence is done at high containment levels.  
                           ^^^^^^^^^^^^^^^^^^^^^^^
So was work with smallpox!!!!!!!   :-)

I agree that these 2 viruses represent very different senerios, vaccinia
virus has a whole set of problems of it's own!!
  _BUT_ one of the reasons that was brought up in favor of destroying
smallpox was that terrorists could get it and infect the world. While polio
may cause serious disease less frequently..... this argument cannot be
applied selectively.

>Hope these ramblings help.


Yes, they did... thanks!!


>Mike
>Dr Mike Poidinger        
>Microbiology, UWA       ==> Animal Welfare NOT Animal Rights       
>Australia                  ==> 668, the neighbour of the beast                 
>mikep at uniwa.uwa.edu.au  ==>Time flies like an arrow, fruit flies like a banana
>-----------------------------------------------------------------------------


Cheers,
      Chris

 Chris Upton  
Biochemistry & Microbiology
University of Victoria
PO Box 3055, Victoria
BC, Canada   V8W 3P6

(604)721-6507
(604)721-8855 fax



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