Re: [Fwd: Bubonic Plague]

From: Andrew Clough (
Date: Thu Oct 04 2001 - 19:38:42 MDT

It does so by infecting both insects and mammals. Fleas that feed on
infected rodents swallow the bacteria, which infect and block their
midguts. The starving fleas feed voraciously, but only regurgitate
the blood they try to swallow - along with the bacteria. So plague
spreads among rodents, often causing only mild disease.

If the infected flea bites a human, however, up to half the victims
die, unless treated with antibiotics. If the bacteria invade the
lungs of such patients, and they cough them out, nearby people may
catch "pneumonic" plague. This is always fatal without treatment.

In eighth grade, the infamous Mr. Watts assigned our class research papers, of which mine was to be on the Black Death.  I learned quite a lot making that 20 something page paper, and I actually haven't had to do a more in depth one since.  I think that this article was very consistent with what I know, except with regard to the pneumatic plague being "always fatal without treatment."  The normal, everyday bubonic plague would probably kill you, the pneumatic plague was very likely to kill you, and the septic plague was the one that would almost certainly kill you.  The septic plague occurs when Y. pestis invades the blood stream instead of the lymph system, and is actually a very fast killer as diseases go.  It could be spread between people by the bites of normal, human fleas in addition to the rat fleas that spread the bubonic (lymph) version.  But I digress...

As I was saying, the pneumatic plague isn't always fatal if you are left untreated, untreated being defined as the care that was available in Europe at the time, bed and food.  It was actually much more contagious in colder climes than in warmer ones.  In fact, 70% of the Iceland population died from it, while Greenland was completely wiped out.  By contrast, it wasn't even noticed in Italy.

Another little thing; the plague doesn't cause "only mild disease" among rodents, or at least doesn't when humans get the disease.  In the main locus, in Mongolia, the rats have developed an immunity.  However, the Chinese, Indian, European, ect rats hadn't.  Y. Pestis is actually even more deadly to rats, its normal host, than to people.  In fact, the fleas that carry the disease don't normally feed on humans, and did so during the plague after all the rats in the area had died.  This is one of the reasons that the quarantine measures put into place by some of the more enlightened medieval rulers had no effect: by the time the plague showed up nearby, all your rats were already infected and you were already doomed.

Still, though Y. Pestis isn't an insurmountable challenge to modern medicine in it's traditional form, a mutant or hybrid variety, particularly an antibiotic resistant one, would be a Bad Thing.

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