Interesting question that somebody here might be able to say something
about or repost to somewhere more appropriate. My excuse for posting it
here is that (a) I know that some people who read this list might be
able to add something; and (b) it could make a good classroom exercise
with numbers added.
On the news last night there was a story suggesting that there has been
more than one case of Creutzfeld-Jacob disease in Canada among
recipients of dura mater grafts. Now, if this is the case, something
very odd is afoot.
Specifically, I would have thought that, brain surgery being fairly
rare (and being a desperate enough measure that a significant proportion
of patients probably do not survive it by the latency period of CJD) the
number of dura mater recipients would number, let us say, in the
thousands rather than the tens of thousands within Canada. CJD itself is
extremely rare in the general population, and one would assume that dura
mater donors would be selected independent of undiagnosed CJD and
excluding diagnosed CJD.
If the obvious model held, we would have an incidence of CJD among
graft recipients only twice that in the population at large. (I'm
assuming here that dura mater is not pooled in storage as were some
blood products such as human clotting factor, and that repeat
transplants are rare.) It seems, from the news stories, as if it is
much higher than this.
Possibly the news stories have it wrong, in which case there is no more
to be said.
If not, the next most obvious conclusion must be that a graft recipient
can develop CJD when the donor, had [s]he lived, would not have. In
other words, the process of grafting dura mater tissue is itself
involved. There seem to be eight possibilities:
prions (in the host brain or in grafted dura mater)
are (created or activated)
by (immune response to foreign tissue or anti-immune drugs).
Any thoughts?
-Robert Dawson
Math & CS
Saint Mary's
.
.
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