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Polio vaccination

Michael McDonough MCM2 at ciddvd1.em.cdc.gov
Mon Oct 17 13:26:43 EST 1994

In article <9410160303.AA23291 at fiona.umsmed.edu> gentry at FIONA.UMSMED.EDU ("Glenn A. Gentry") writes:
>From: gentry at FIONA.UMSMED.EDU ("Glenn A. Gentry")
>Subject: Re: Polio vaccination
>Date: 15 Oct 1994 20:06:48 -0700

>Before we congratulate ourselves on eliminating polio (at least from the
>Western hemisphere) we need to remember that the disease *polio* was never
>very common, especially in 3rd world countries where most of the population
>had subclinical infections as infants. Until everyone worldwide is immunized
>for a period of time the virus could still be around, waiting for the
>opportunity provided by unprotected segments of the populations.
>   I am reminded of Mark Twain's comment that "reports of my death are
>greatly exagerrated" and the remark of the Surgeon-General of the U.S. in
>1969 (I think that is the right year) that "we can now close the book on
>infectious diseases".
>                        Glenn Gentry
>gentry at fiona.umsmed.edu

My colleagues and I have been an integral part of the polio eradication 
effort.   As such, I would like to clarify several points made by Mr. Gentry:

     1. Polio was a very common problem, not only in 3rd world countries but even in the U.S.
where in 1952 alone, over 21,000 cases of paralytic polio were reported.  There are an estimated
1.6 million U.S. survivors of paralytic polio epidemics. (Birk, TJ. Poliomyelitis and the post-polio
syndrome: exercise capacities and adaptation- current research, future directions, and widespread
applicability.  Med. Sci. Sports Exerc., vol. 25, no. 4, pp466-472, 1993.)
     In 1990, an estimated 150,000 cases of poliomyelitis were occuring annually in 70
countries where the disease is still endemic.  In 1991, India reported over 6000 cases. (Progress in
the Worldwide Polio Eradication Effort, EPI Newsletter, vol. XIV, no. 6, December 1992).

     2. It is not necessary for every single person to be immunized.  As shown in the Americas,
vaccine coverage >80-90 % (known as "herd" immunity) is often sufficient to 
break the chain of transmission; and humans are the only natural reservoir for 

     3. Unvaccinated segments of the population are at risk due to virus importations from
endemic areas.  However, these are usually very small populations and the risk of transmission to
the general, vaccinated population is small.  (See #2 above and reference #2 above for discussion
of the Netherlands outbreak  in 1992).

In addition, the laboratory and suveillance network established in the Americas for polio, is a
foundation from which we can attack other diseases.  That is already happening in the Americas
as resources and experience from the polio campaign are slowly being transferred to diseases such
as measles.

We SHOULD congratulate ourselves for achieving a major milestone in our fight against polio. 
We should take a moment to say "Well  done!!".  Then we should roll up our sleeves and get back
to work.  There is still a lot work ahead.

Michael McDonough
MCM2 at ciddvd1.em.cdc.gov

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