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

Re:Nature provides the solution

[Feral Nerd]

The reason Europeans were so susceptible to the plague is that they were Europeans, just as the reason Native Americans were so susceptible to small pox was that they were Native Americans. Inbreeding leads to weakness, crossbreeding leads to strength.

I agree that crossbreeding builds a strong population and pure bloodlines (aka. inbreeding) leads to weak populations but the rest of your post is wrong. There was steady gene flow between Asia and Europe for millennia whereas the aboriginals of the Americas were isolated after the end of the last ice age and the submergence of Beringia which cut the land bridge between Asia and North America. There were some old-world diseases that caused devastation among Native American populations and there were some new world diseases that caused devastation in the Old World. However, some of the pandemics that wiped out the native populations of the Americas (and that were previously thought to have been introduced pathogens) would in the light of modern research seem to have been entirely home grown. For example the pandemic that wiped out the Aztecs after the Spanish invasion seems to have been a hemorrhagic fever endemic to the Americas. Scholars in the past wrote a whole lot of stuff about pandemics without having the foggiest notion of which pathogens had been involved and those writings unfortunately remained gospel until very recently. Until only a couple of decades ago we had only a limited idea of whether the Black Death pathogen was the same as the modern plague bacteria, there were divided opinions. Some thought he plague of 1346 was an influenza. The last time I looked plague DNA had indeed been found in ancient remains but we still do not know if the Black Death and the Justinian plague were the same or not, the Justinian plague could have been something else altogether. There is also this persistent myth, born out of the 19th and early 20th century fascination with the orient, that all culture flowed from the east (i.e. Ex oriente lux = From the east the light), that medieval Europeans were somehow dirtier, more ignorant and more primitive than oriental people and that that is why the plague spread so rapidly in Europe. Roman bathing culture did not just evaporate with the fall of the old empire and throughout the Middle Ages there were bathhouses in many cities and towns in Europe (in the 13th century Paris had 32 bathouses). If the Medieval European really was so dirty and Asians so clean why did a pandemic spread by fleas spread from Asia to the West? You'd think it would originate among the dirty Europeans and then travel east and dissipate when it reached Asia because of the supposedly superior hygiene of medieval period Asians who would not, or so the conventional theory goes, have had fleas. In actual fact the Plague ravaged Europe and Asia pretty much equally and Asians of the 14th century seem to have been just as flea ridden as their European contemporaries. For example in 1334, a pandemic that was probably the same black death that ravaged Europe a decade later killed 5 million people in Hebei Province China with a death toll of about 90%.

Re:Math is fun

[Himmy32]

Do you? http://lmgtfy.com/?q=define%3A...


decimate

verb

1. kill, destroy, or remove a large percentage or part of.

"the project would decimate the fragile wetland wilderness"

2. historical - kill one in every ten of (a group of soldiers or others) as a punishment for the whole group.

As an upside of getting the plague

[Khyber]

Survivors of the Back Death seem to acquire part of a beneficial genetic mutation that gets passed on in full if they breed with another Black Death survivor - resistance to most known forms of HIV.

http://www.eurekalert.org/pub_...

Re: As an upside of getting the plague

[Anonymous Coward]

This has been experimentally disproven. The CCR5delta32 mutation does not protect against plague: http://www.nature.com/nature/journal/v427/n6975/full/427606a.html

Re: As an upside of getting the plague

[Anonymous Coward]

They didn't say protects against plague, they said protects against HIV.

Re:Usage changes meaning

[JustAnotherOldGuy]

My my, someone seems prickly today....too much starch in your undies? Why so much hatred? Is that your typical response to someone who disagrees with you? If so, that's kind of sad.

Anyway, yes, words can change colloquial meaning over time.

For example, "literally" has now come to mean "figuratively", due to the excessive hyperbole that most people seem to engage in these days.A complete reversal of meaning which seems stupid to me.

That said, tthere are plenty of places where reversal of meaning has happened, such as the word "nice". It used to be an insult of sorts, meaning ‘stupid’ or ‘ignorant’. Later it came to mean ‘coy' or 'reserved’, and then it morphed again to mean 'subtle' and/or 'fine'. It finally became accepted in the current sense, which is 'good' or 'pleasant'.

So yeah, it does happen. But as a cranky old word-Luddite, I'd prefer to use "devastated" in place of 'decimated'. Maybe in 50 years when I'm happily dead and buried the word will be uniformly accepted as having the same meaning as "devastated". :)

And now I must go have lunch, because I'm literally starving to death here.

Cheers

Bubonic Plague

[tuxgeek]

I used to live in Tahoe.
Occasionally during the summer months, someone would contract bubonic plague after their house cats were outside and near ground squirrel burrows.
It is transmitted by fleas of the common ground squirrel in the area. Don't remember the species.

The infestation of infected fleas usually gets worse in drought years.

Plague fleas are found all over the sierras, Yosemite as well.