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Re: H1N5 (and Bakker's virus extinction hypothesis) now H5N1
At 19:27 2006-05-14, Dora Smith wrote:
It is not unlikely that epidemic disease, possibly of more than one sort,
played a role in the end of the dinosaurs. Ecological catastrophe would
have left them more vulnerable than usual to whatever disease came along,
and often all a disease needs to gain a foothold is a starving population.
For instance, plague became pandemic in Europe specifically because sudden
climate change immediately before the plague arrived in Europe left great
numbers of people starving. Bubonic plague had actually been around in
Asia and the Near East for millenia before that but never with such
dramatically catastrophic consequences. Bubonic plague still exists in
our environment, but people seldom catch it, even in the Third World where
large numbers of people catch any disease you can name.
While the point about lowered resistance is generally valid, it is much
less valid for plague than for most diseases. Plague has a very high
mortality irrespective of the physical/nutritional status of the victim,
and the plague epidemics of the past (unlike many other diseases), affected
all classes badly.
Bubonic plague as far as is known has *not* been around for millenia, at
least not in Europe and the Middle East. There is as a matter of fact no
indication that plague ever occurred there before the Justinian Plague
(542-551). Plague then stayed active around the Mediterranean until about
750, after which it disappeared, not to return until 1347, and once again
disappearing (from Europe at least) in the eighteenth century. Incidentally
whether the Justinian plague cycle affected Europe north of the
Mediterranean is quite uncertain. There is almost no written information
from this period (the darkest part of the "dark ages"), but there is a
great deal of archaeological evidence for depopulation at this time.
It is correct that *Yersinia pestis* is now endemic in many areas (much of
subsaharan Africa, Madagascar, large parts of Southern, Central and Eastern
Asia, the southwestern US and parts of South America).
Howevver it is *not* correct that people seldom catch it in Third World
countries. Small but nasty epidemics occur regularly, particularly in
Africa and Madagascar. The reason they don't become major epidemics is that
plague responds very well to antibiotics, even the older and cheaper types,
and as long as the epidemics don't become major they are unlikely to
attract any attention from the media. Fortunately, since *Yersinia pestis*
spends most of it's time in animal hosts it has been slow to evolve