In article <m0seHYM-0004WHC at uctmail.uct.ac.za>,
Ed Rybicki <ed at molbiol.uct.ac.za> wrote:
>>I am a little disturbed by all this harping on the apparent
>conservation of the Ebola virus genome over time, and the constant
>comments about whether this is due to it's having been in a fridge,
>or having an especially accurate RDRP.
In my case, at least, no conspiracy was implied. I was wondering if
Ebola could survive on its own somewhere indefinitely, rather than
replicating in a host. (For example, in dry soil in a cave, or in
the carpeting of an office.)
Your comments about slow mutation in carrier species are well taken. On the
other hand, in my ignorance I find it plausible that humans could screw up.
Given the careless actions and the unmanageable difficulties documented in
Garrett's _The_Coming_Plague_, it seems reasonable to wonder if humans could
make disastrous mistakes.
It's also not inconceivable that somebody could do something on purpose.
After all, there was the twerp who was buying plague bacillus through
the mail on false pretenses, and there are various people who blow
people up, or nerve gas them. One of them might go for some Ebola, for
all I know.
Am I paranoid? Is _The_Coming_Plague_ paranoid? I found it pretty
compelling, and am wondering how seriously I should take it, and what
constructive actions are being taken to limit risks.
I read a pooh-poohing review in the New Republic (by the Washington Post's
science editor) of _The_Coming_Plague_ and _The_Hot_Zone_, and unfortunately
I didn't find the guy's dismissal of those books nearly as convincing as
the books themselves. It seemed to me that he didn't have a deep grasp
of evolutionary principles.
For example, he argued that plagues tend to be limited in scope because
viruses mutate so as not to kill their hosts. That seems like it's true
for *most* plagues, but that it's not necessarily true for viruses that
have a successful strategy for propagating before they kill their hosts.
(Or when they kill their host, by crashing out with gazillions of viruses.)
He also argues that we've had international travel spreading plagues
before, and they haven't killed us all yet, so we shouldn't get all worried.
I found that very unconvincing, for several reasons:
1. AIDS, which has a similar-but-different "strategy" of transmitting
before killing its host, doesn't seem to have gotten much nicer after
spreading to a very large number of people. In logarithmic terms,
it's already most of the way to killing most of us---it would only
need a few more generations to get to all of us, if it were easier
spread. So I'm not comforted by the reassurance that viruses have
to become less harmful as they propagate.
2. Plagues have killed significant fractions of large populations
before. Even if a plague only killed of 1/3 of the people in
the world, it could be pretty inconvenient, both for those killed
and the survivors trying to keep the world economy going after
3. The reviewer argues that spreading foreign viruses around is, in the
long run, a good thing, because we develop immunities to more things.
(What doesn't kill us makes us stronger, I guess.) This seems like
small consolation to the Native Americans who died when the white
people brought them plagues. The writer also seems to be making the
argument that European stock is more robust than Native American
stock, which is why the converse effect didn't happen in a big way,
and that it's due to European's greater exposure to a wide variety
of diseases over centuries of foreign commerce. Is this true?
Again, #2 applies---I don't want to be in the 1/3 that dies for
the future good of the species, and I'm not convinced we couldn't
have plagues much worse than the black death.
4. There may have been many plagues that killed off whole populations
of regions, but "burned themselves out" because they killed their
hosts faster than they could gross geographic boundaries. It
seems to me that with intercontintal jet travel, cars, trains,
buses, and other vehicles, things could be different next time.
We've changed the environment for plagues in ways that may make
it more feasible for a highly contagious virus to kill its host.
(Sailing ships don't seem nearly as good at this---everybody on
the boat may die, and it just doesn't show up again.)
The best countervailing argument I've come up with is that it hasn't
happened yet, so maybe it never will. That doesn't convince me; the
AIDS and Ebola examples seem close enough to the Big One that I'm somewhat
concerned, and it only seems likely that it probably won't happen Real
Soon. (Which may give us time to do something about it.)
| Paul R. Wilson, Comp. Sci. Dept., U of Texas @ Austin (wilson at cs.utexas.edu)
| Papers on memory allocators, garbage collection, memory hierarchies,
| persistence and Scheme interpreters and compilers available via ftp from
| ftp.cs.utexas.edu, in pub/garbage or http://www.cs.utexas.edu/users/oops/)