Black Death not initiated by a plasmid OR a moron? Turns out it *we* were the morons!

Me, September 1, 2011:

Black Death not initiated by a plasmid? My money is on a moron.
Phages can encode for gene groups called morons.

I am not joking.

These are viral genes that dont code for anything the virus wants, like structural proteins, or enzymes the virus needs-- They are genes that make having the virus around attractive to the bacteria. And few things are more attractive to a pathogen than making you sick, thus spread the bacteria faster than if you werent pooping/oozing/puking/etc.

I bet its a moron.

Nature, October 12, 2011:

A draft genome of Yersinia pestis from victims of the Black Death
Here we report a reconstructed ancient genome of Yersinia pestis at 30-fold average coverage from Black Death victims securely dated to episodes of pestilence-associated mortality in London, England, 1348-1350...Comparisons against modern genomes reveal no unique derived positions in the medieval organism, indicating that the perceived increased virulence of the disease during the Black Death may not have been due to bacterial phenotype. These findings support the notion that factors other than microbial genetics, such as environment, vector dynamics and host susceptibility, should be at the forefront of epidemiological discussions regarding emerging Y. pestis infections.

Welp. Shows what I know, dont it?

The bacteria that caused the Black Plague had no unique super scary plasmids. They had no unique super scary morons. They dont seem to have any unique super scary mutations.

The bacteria that ravaged the human population in Europe... is pretty much the same bacteria we can easily treat with tetracycline today.

I dont know about you, but this BLEW MY MIND.

A collision of *human* factors-- human behaviors, human sociology, not enough food, no clue about sanitation or germ theory or quarantines, no antibiotics or medical advancements we view as 'basic' in the modern world, Europeans never being exposed to this kind of bacteria before...

There is no scary mutation one reversion away.

There is no reservoir of a scary plasmid or a scary moron lurking in the shadows, waiting to reemerge.

Turns out, what might have killed so many people during the Black Plague... was human ignorance and bad timing:

The Black Death is a seminal example of an emerging infection, traveling across Europe and claiming the lives of an estimated 30âmillion people in only 5âyears, which is much faster than contemporary rates of bubonic or pneumonic plague infection and dissemination. Regardless, although no extant Y. pestis strain possesses the same genetic profile as our ancient organism, our data suggest that few changes in known virulence-associated genes have accrued in the organism's 660 years of evolution as a human pathogen, further suggesting that its perceived increased virulence in history may not be due to novel fixed point mutations detectable via the analytical approach described here. At our current resolution, we posit that molecular changes in pathogens are but one component of a constellation of factors contributing to changing infectious disease prevalence and severity, where genetics of the host population, climate, vector dynamics, social conditions and synergistic interactions with concurrent diseases should be foremost in discussions of population susceptibility to infectious disease and host-pathogen relationships with reference to Y. pestis infections.

We cant lay all of the blame of The Plague on the bacteria. It wasnt just the bacteria. It was us, and old fashioned bad luck.

*mind-blown*

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So...is this an example of evolution in action? Does this mean all the susceptible people died and the remainder were by consequence simply left more resilient descendants? Otherwise, what were the other contributing factors that made it so lethal that don't exist today? Nutrition? Climate? Better sanitation? So many questions!

@ Justicar - "Bring out your dead!" "I'm not dead."

@ WLU - Changes in MHC frequency might play a role, though then you'd expect non-european descendants to be just as susceptible. I don't know if there's been any research on this...

@Kevin: ZOMG! We watch the same shows on the history channel! It's how I learned about ancient astronauts, mega-quakes, and other true facts.

So it was human factors, just like all the health problems of today. Condom use, vaccination, HPV, antibiotics in animal feed, health insurance, legalization of tobacco and criminalization of marijuana, hunger, obesity, global warming, unemployment, war, terrorism, idiocy.

I've also heard the argument that today's forms of plague are less virulent because it acted as a selection pressure on humans: the most susceptible were killed over the years, leaving the human population as a whole less vulnerable to it. Add in the advances in medicine, hygiene, and public sanitation, and the plague recedes as a threat.

Seems to still be incredibly virulent amongst Prairie Dogs and is quite a killer for humans if not treated quickly from what I understand. It is amazing to me that it hasn't evolved much since then but I'm not too surprised that it didn't evolve to better exploit humans if it has always mainly existed as a rodent pathogen and it is that host parasite interaction that dominates.

There is no reservoir of a scary plasmid or a scary moron lurking in the shadows, waiting to reemerge.

You sound so disappointed.

By Daniel Schealler (not verified) on 13 Oct 2011 #permalink

You sure the wheelbarrows of dead people being brought out wasn't a major factor. byprf MediterraneanMenu canada. It is fantastic to me that it hasn not evolved much since then but I'm not too surprised that it didn't evolve to better exploit humans if it has always mainly existed as a rodent pathogen and it is that host parasite interaction that dominates.

Maaaaaybe a major factor is that not everyone has rats and their fleas in the house today.

By mo (one of Abb… (not verified) on 13 Oct 2011 #permalink

Hey, Abbie: You obviously haven't read what the Institute of Creation Research has to say about it. See The Plague: Birth of a Killer. They say: "... disease-causing germs resulted not from direct creation or Darwinian evolution, but rather from the sin-cursed condition of this world, in which all living systems are subject to corruption and decay."

SC, I love that argument because it proves that we're vastly more virtuous today than when Europe was 100% Christian and overwhelmingly devout.

By D. C. Sessions (not verified) on 13 Oct 2011 #permalink

I've also heard the argument that today's forms of plague are less virulent because it acted as a selection pressure on humans

That's a good point. If there has been selection for less susceptibility in humans, I would expect there's some variation in this trait in modern human populations since some areas have historically suffered many more epidemics than others.

Uh, and HIV was spread around the country via a promiscuous flight attendant.

In other words, us and bad luck.

History tends to repeat itself.

Damned sluts.

I thought that this HIV thing was starting to make its way through all the wrong kind of whores like a hundred or so years ago?

Mo, I keep pet fleas (payback for all the nights my cats wake me up) and wild pet mice (to distract the cats). No idea what you're talking about!

The 10% of the european population with the CCR5 deletion - makes them resistant to HIV and fucked if they contract West Nile Virus - is hypothesized to have a selection pressure by the plague as a cause.

http://qjmed.oxfordjournals.org/content/99/8/497.long
(seems like a bad hypothesis though.)

Justicar: a whole ecosystem with the fleas as top predators :P

By mo (one of Abb… (not verified) on 13 Oct 2011 #permalink

It's possible that plague was more than one disease as well. There are reports from the time that make it sound a bit more like a haemorrhagic fever, and there's quite a good argument in a book called "biology of plagues" detailing the well described outbreak in the village of Eyam, Derbyshire, England. Eyam was pretty much wiped out (they sealed themselves off) but the thing is - there weren't any rats. The village is built on limestome - no basements etc, not rat hidey holes. Some even think it might have been haemorrhagic measles... Not much evidence though!

Which makes it likely that the underlying cause was the end of the Medieval Warming period. With a lower temperature food became scarcer and Europe's polulation got nearer the edge. Any duisease would then be likely to trigger a die off.

Assuming Mannis wrong and the Medieval Warming happened and also assuming that warmth is preferable to cold. Neiother of which may be discussed on "scienceblogs".

By Neil craig (not verified) on 14 Oct 2011 #permalink

Eyam was pretty much wiped out (they sealed themselves off) but the thing is - there weren't any rats. The village is built on limestome [sic] - no basements etc, not rat hidey holes.

Although I am not disagreeing with the premise that the plague was a convergence of diseases, the rats associated with the plague were not "sewer rats" (Rattus norvegicus). The culprit is usually ascribed to black rats, or roof rats (rattus rattus) so a lack of subterranean structures is not a barrier. Indeed, it would be a boon to black rats as they would have little competition.
The other point many forget is the Plague of Justinian (also hypothesized to be bubonic plague) had similar mortality rates. One can find common historical threads (low sanitation, high incidence of malnutrition, poor medical practices, and so forth) between the two. It's unknown whether other maladies accompanied that outbreak.

By Onkel Bob (not verified) on 14 Oct 2011 #permalink

At our current resolution, we posit that molecular changes in pathogens are but one component of a constellation of factors contributing to changing infectious disease prevalence and severity, where genetics of the host population, climate, vector dynamics, social conditions and synergistic interactions with concurrent diseases should be foremost in discussions of population susceptibility to infectious disease and host-pathogen relationships with reference to Y. pestis infections.

Er well yeah. History is almost always more complex than the 'current resolution' (whenever current may be) allows. The sheer scale of social change in Europe in the middle of the 14thC, coupled with the presence of a disease that was uniquely identifiable (bubogues)and popularly associated with the superstitions of the day (mark of the devil etc) ensured that a story which coupled disease and social shange in popular conciousness would become an enduring historical explanation. How much Y.pestis was solely responsible for the widescale loss of life in the 10 years centred on 1350 will never be certainly known but a single Europe wide picture is unlikely to form part of a realistic historical epidemiology. Patterns of disease in urban centres may well demonstrate commonality, but most of Europe's population was rural and local conditions may provide numerous variations. There is a long standing proposition for there having been highly localised pockets of disease resistance in England, based on records from geographically close plague affected villages where death rates differed by orders of magnitude. But explantions other than resistance are available and a confluence of factors probably applies to each individual community extant across the whole of north and west Erope in and around 1350. Contempory perspective undoubtedly affected reporting and subsequent interpretations of The Black Death and the role of widespread millenielism particularly should not be discounted.

Hmm, I don't know if this is a good thing or a bad thing. On the one hand, as Abbie observes, there's no dangerous plasmid out there that can just pop in and make everything awful. On the other hand, it does show how circumstances can take an otherwise normal disease and make it orders of magnitude worse.

Pffft.

Just means going back to the entomological drawing board. Most of the theory on flea infestation "load" and human populations is junk based on the European human flea which didn't show up until after the first wave (South American).

The carrier was probably Xenopsylla cheopis (not identified until 1903) which is a much nastier less discriminating beastie.

This is a job for the flea people and cladists(oddly enough, the flea masters are at Brigham Young Biology).

The historian's job is account correlation but not for black death.

The key will be the level of infestation regarded as remarkable (hint for aspiring medievalists: Murder of Thomas Becket) and how high was the carrying load of fleas in the only people who regularly traveled.

Considering everybody from the bishops to the Muscovite princes were wearing hair shirts, it might be better to calculate what the carrying load of Xenopsylla cheopis is for a guy in a monkey fur vest.

By Prometheus (not verified) on 14 Oct 2011 #permalink

Um, it is elegant though, the very same thing happend to native american and native australian populations when they encountered small pox.

Shifting between 25 and 50% death ratio for both of them from a disease that was foreign at the time.

We really live in the best times offered to live so far!

#23 and how high was the carrying load of fleas in the only people who regularly traveled.

The challenge then is to identify travelling patterns in societies in a state a flux; even before 1347/8 much of Europe was going through social and economic change. In England and Wales the human population had reached its likely highest ever density, with much land that had previously been considered marginal being occupied and exploited, and trade routes being significantly extended; in essence more people were moving about. The outbreak of disease itself can be a cause of increased movement via population perturbation, making the identification of 'typical travellers', particularly in urban centres, somewhat difficult.

By infidelium@hot… (not verified) on 14 Oct 2011 #permalink

One argument against Yersinis pestis causing the Black Death was the fast rate of spread within a town or castle, which did not correlate with the length of time it takes plague to cycle through the rat flea.

The Colorado plague studiers discovered that the human flea (which is really scarce now) is capable of transmitting plague in a much shorter cycle. A heavy load of those in the environment and you could see the explosive spread seen in the Black Death years.

By Tsu Dho Nimh (not verified) on 15 Oct 2011 #permalink

"The challenge then is to identify travelling patterns in societies in a state a flux; even before 1347/8 much of Europe was going through social and economic change. In England and Wales the human population had reached its likely highest ever density"

Again, that is kind of a meh because we have a lot more records than people assume. A major vector that has been allowed to sit fallow is wheat transmission.

Fleas are tropical in origin, as soon as the host body starts to cool they explode outward looking for warmth. They will hibernate and hatches can be delayed, as was probably the case with the Eyam clothing shipment but if they can find a mass maintaining a 82.4 degree F ambient (center of a bushel of wheat in a wooden container) they are all over it. I've seen infestations of fleas in European wheat....spooky.

Incorporate infected default global currency into the system and you are talking rapid transmission with any famine amping up the equation and if we have Xenopsylla cheopis doing the damage you are tossing in typhus.

When I was a working medievalist I did comparative studies of trial transcripts and onion peeled hundreds of hagiographies to the amazement of colleagues who were grateful for someone who would attack such boring but fruitful aspects of the discipline.

Good luck finding some poor bastard willing to spend the next five years rummaging through the grist tax and shipping records.

I believe there were over 16,000 grist mills in England alone, by the time of the first wave.

Medievalists are as lazy as anybody else. The fact that they handed off their easiest hypothesis to epidemiologists and it didn't work isn't that great a mystery.

Their problem now is that the alternatives involve an enormous amount of work that is not going to provide source material for lucrative popular historical writing.

Who is going to buy "The Black Death: wheat and the wrong flea" when they can get "Land of Women: Tales of Sex and Gender from Early Ireland"?*

Odds are the whole proposition will wind up as a turf war between the historians, caftan and ethnic jewelry festooned shmoos from the gender and comparative religion departments or worse sandaled hygiene challenged baby boomer Lotharios from English department Chaucer projects.

*Lisa M. Bitel is seriously screwy. She used to be a real scholar but she got to be a department head through the popular promotion of the proposition that Northern Medieval society revolved around girl on girl action.

P.S. I'm fine with girl on girl action but let's keep it on Cinemax and out of the posterity of Kildare Abbey (or at least limit it to the oratory...hurr hurr hurr).

P.P.S. Sorry to be so bitchy. The old scar tissue from academia tends to itch a little when the weather changes.

By Prometheus (not verified) on 17 Oct 2011 #permalink

I'm not certain why you're so surprised.

I mean this is the same old story that comes around every now and then. Look at maternal death rates in the 1800s, in some places nearly 40% of women died in child-birth. All because of the environment in which those births were taking place.

I always thought that common wisdom (though often wrong) held that the discrepancy between then and now was most likely due to the state of human society. The confirmation of this idea is somewhat surprising (given the recent pronouncement that it was a different strain than what is currently around and our expectations of different molecular mechanisms of virulence that may only be subtly different but which could have huge effects [we often do see this in studies involving bacteria, fungi and viruses, as I don't need to tell you]) but it shouldn't be "mind blowing."

I think what lots of people tend to forget is that every year in the southwestern US, a handful of people still get the Bubonic Plague. When I was a kid my parents warned us to stay away from prairie dogs because they carry it.
This is still a disease that kills people, even in this day and age with sanitation and good medical care. The relative poverty of this area might be a factor in the mortality rate--people go untreated instead of getting to a hospital, but it is still a dangerous pathogen. I'm not really surprised, in light of this, that it could have wiped out a third of Europe, given that even the cleanliness of a pit-toilet is light-years ahead of "nightsoil" disposal in the 1300s.

By tamakazura (not verified) on 17 Oct 2011 #permalink

tamakazura@#30

"I think what lots of people tend to forget is that every year in the southwestern US, a handful of people still get the Bubonic Plague."

Good point.

They are even more ignorant of 1924 and the WWI veterans being called out to quarantine 2,500 people in Los Angeles while the county health department burned down their houses and shot all the squirrels.

I can't remember the 1903 death toll in San Francisco but it was over 150 before they figured out what was going on.

The numbers are probably a lot higher than reported due to early misdiagnosis and trying to keep it quiet.

"...even the cleanliness of a pit-toilet is light-years ahead of "nightsoil" disposal in the 1300s."

They were still hauling chamberpots up and down the White House stairs in 1866.

Versailles has over 1300 rooms and only one flush toilet.

Among the greatest inventions in the prevention of disease sits (sorry) the humble Twyford trapless toilet.

By Prometheus (not verified) on 17 Oct 2011 #permalink

@Prometheus #28 - well with a 'nym' like yours we have to expect you to be a bit liverish. Thanks for the offering of Schadenfreude, your academe expositions raised a wry smile -but honestly "I feel your pain". Even with history left free of Her-story, other-story etc, it was always the story telling that sold the books and dragged in the students, and no one should expect the practioners of hard science to be any more immune to the romance of the stories that 'historians' tell than the rest of us.

By In Vitro Infidelium (not verified) on 17 Oct 2011 #permalink

Evening Abbie,

Not to be too flippant about this but err.. we kinda learned this in like history class - you know the 'human' and social elements minus the sciency stuff.

Though I seem to recall fleas were mentioned a lot, Oh and hygiene, and lavender (popular remedy more so though for the stench I should think) lol

Funny old world sometimes isn't it?

"Not to be too flippant about this but err.. we kinda learned this in like history class - you know the 'human' and social elements minus the sciency stuff. Though I seem to recall fleas were mentioned a lot, Oh and hygiene ..."

Somebody doesn't read my blog (*makes sad face*). There are quite a lot of reasons not to believe what you learnt in school about the Black Death, rats and fleas; the triad theory just doesn't fit the facts. Neither do off-the-cuff mentions of human factors such as malnutrition.

"I've also heard the argument that today's forms of plague are less virulent because it acted as a selection pressure on humans ... "

There are similar theories, but they simply don't add up to being a rule, despite speciously looking like one; virulence and lethality depend on other factors. How's TB going, for example? How about XDR shigella?

Now there's a thought. MDR or XDR shigella on the move out of India.

BTW, in case anyone's interested: not only is the Black Death still a msytery, but why leprosy practically disappeared from northern Europe after the Black Death, despite having been endemic till then, is also a mystery.

"....leprosy practically disappeared from northern Europe after the Black Death, despite having been endemic till then, is also a mystery."

Tends to be blamed on lepers being confined to leprosaria which were also the restricted portions of the lazerets where all the dead and dying were literally piled up. At the time of the first wave, lepers had acquired special religious status through the Order of Saint Lazarus but they were still dependent on attendants and charity for survival.

A testable enough proposition that should come up in the half dozen plague trench graves being excavated now....of course first we have to devote two years about a million bucks on the Vampire Skull booga booga...sigh.

http://www.telegraph.co.uk/news/worldnews/europe/italy/4959363/Mediaeva…

By Prometheus (not verified) on 19 Oct 2011 #permalink

There are similar theories, but they simply don't add up to being a rule

Who said it was supposed to be a rule? Evolution for increased resistance is one possible factor, not something that is argued to occur for all human diseases.

wait.... are you blaming the victim?

By greylander (not verified) on 13 Nov 2011 #permalink