The Mutant Genes Behind the Black Death

An anonymous reader writes: Each year, 4 million people visit Yosemite National Park in California. Most bring back photos, postcards and an occasional sunburn. But two unlucky visitors this summer got a very different souvenir. They got the plague. This quintessential medieval disease, caused by the bacterium Yersinia pestis and transmitted most often by fleabites, still surfaces in a handful of cases each year in the western United States, according to the Centers for Disease Control and Prevention. Its historical record is far more macabre. The plague of Justinian from 541 to 543 decimated nearly half the population in the Mediterranean, while the Black Death of the Middle Ages killed one in every three Europeans.

Now researchers are beginning to reveal a surprising genetic history of the plague. A rash of discoveries show how just a small handful of genetic changes — an altered protein here, a mutated gene there — can transform a relatively innocuous stomach bug into a pandemic capable of killing off a large fraction of a continent.

The most recent of these studies, published in June, found that the acquisition of a single gene named pla gave Y. pestis the ability to cause pneumonia, causing a form of plague so lethal that it kills essentially all of those infected who don't receive antibiotics. In addition, it is also among the most infectious bacteria known. "Yersinia pestis is a pretty kick-ass pathogen," said Paul Keim, a microbiologist at Northern Arizona University in Flagstaff. "A single bacterium can cause disease in mice. It's hard to get much more virulent than that."

Comments

Math is fun

[Anonymous Coward]

"decimated nearly half the population"

So it killed 5%?

But it did not kill all!

[140Mandak262Jamuna]

Half the population survived and got immunity to it. These pathogens traveled along the trade routes by land to three large population centers, India, China and Europe, Arabia and the Silk route forming land trading routes. They will leave behind an immunized population but sustain themselves by hitting these population centers and rebounding some 20 years later to find fresh unimmunized populations. And several such iterations strengthened the immunity of all the inhabitants of the old World. In each iteration these pathogens got more and more lethal. When the sea routes opened these pathogens "seeded" multiple locations simultaneously in Europe creating very virulent outbreaks.

When Europeans arrived to colonize the New World, their small population should have been wiped out by the diseases unfamiliar to them in the New World. But they were not. Instead the much larger (than the colonists) New World population got devastated by the Old World diseases.

This explanation came out as a 12 page (The arrow of disease) article by Jared Diamond in 1992 in the Discover magazine. Later it was expanded into a Pulitzer winning book, Guns, Germs and Steel

Re:Usage changes meaning

[PopeRatzo]

If the soldiers grossly underperformed, the commander would line them all up and order that every tenth man be beaten to death by the nine men around him.

Can we adopt that policy for GOP presidential candidates? It would make the debates more interesting and the base would love it.

Re: Nature provides the solution

[Barsteward]

there is nothing like a good joke and that's nothing like a good joke