Smallpox?

[Ken Brown]

Nomen Nescio wrote:
> 
> James Donald writes:
> > The original vaccine was based on cowpox, the nearest
> > relative of small pox.  However it was insufficiently
> > effective and reliable, and so was furtively replaced by a
> > weakened strain of smallpox, which was grown on cows.  The
> > sellers of the vaccine continued to represent it as cowpox,
> > but it was in fact a mild variant of the real thing,
> > smallpox.
> >
> > One reason for ending routine smallpox vaccinations was fear
> > that the vaccine might re-evolve virulence.
> 
> You are full of shit.  The smallpox vaccine is not made from cowpox
> or from smallpox (variola) virus.  It is made from the vaccinia virus.
> Did you ever wonder where the word "vaccine" comes from?
> 
> The reason routine smallpox vaccinations ended was because some people
> have a bad reaction to the vaccinia virus, even though a strain is used
> that is generally benign.  Since the vaccination was thought to confer
> no benefit and does carry some risk, it was discontinued.
> 
> Do a google search on "smallpox vaccine" next time before you spout off
> with ignorant garbage like this.

And google is of course the fount of all wisdom?

As I think someone else pointed out, the original vaccine *was* based on
cowpox. Inoculation with dried up pustules from smallpox victims had
been known about since at least the 10th century in China and by the
18th had spread all over Asia and Europe. However there was apparently a
1-5% chance of causing smallpox, so it was a desperate remedy. Jenner
had the idea of using cowpox pustules from milkmaids. They thought that
cowpox was caught from cows so called it "vaccination". 

As you say (& I didn't realise till I looked it up just now) it was
later based on vaccinia virus, which is of unknown origin. Just turned
up in a lab one day. It is called "vaccinia" because it was first
discovered in a vaccine.  It probably isn't a recent variation on either
smallpox or cowpox because parts of its genetic sequence are less close
to either of them than they are to each other. (Which might be a clue
that other pox viruses could be used for immunisation as well). Vaccinia
is *not* harmless - people have died of it, and it has become endemic in
the water buffalo population of India, from where it sometimes infects
cows and very rarely infects humans. It might possibly have originated
as a bovine disease, maybe introduced by mistake for cowpox

Smallpox vaccine is still apparently available to people who work in
labs on other poxes, and to medical staff in the (small) part of West
Africa where monkey pox is a human health problem.

Just out of interest, cowpox is *not* a natural disease of cows, but of
rodents, probably originally susliks or gerbils.  It seems that cows can
catch a mild form of it when in close proximity to rodents (such as in
18th century English barns in winter) as can humans. Similarly monkey
pox is originally a disease of squirrels, but was noticed first in
monkeys.

Smallpox isn't likely to be a war-winning weapon, though it could cause
a great deal of terror. It spreads slowly enough so that any country
whose pharmaceutical factories haven't been blown up by cruise missiles
could probably tool up in time to prevent an epidemic, helped by some
sensible quarantines. There are many potential low-tech vaccines. It
kills 10-30% of victims, slowly, and many people in Europe and Asia have
some hereditary immunity or residual effect from vaccination. If you
used it against an army you are likely to end up with very, very, angry
enemies, mostly still capable of fighting.

There are many other poxviruses such as volepox. There is even one
endemic to the USA: skunkpox. You Americans just have to inject yourself
with pus from a poxy skunk if you are worried. Personally I'm much more
scared by nerve gasses. No time to prepare, no practical precautionary
measures anyway.

Details not from Google, but from  Gilbert &7 Allison (1998)
"Vaccination and Immunisation" in Hugo & Russell "Pharmaceutical
Microbiology", 6th edition,  (Blackwell's Oxford) and also from Fenner
(1996) "Poxviruses", chapter 84 of "Field's Virology", 3rd edition
(Lippincott, New York).

Ken Brown (who is a microbiologist when he has his lab coat on)