New study suggests human fleas and lice were behind Black Death, not rodents

January 16, 2018 by Bob Yirka, Phys.org report
Credit: CC0 Public Domain

A team of researchers with the University of Oslo has found evidence that suggests human fleas and lice, not rodents, were behind the spread of the plague that killed millions of people over the course of several centuries. In their paper published in Proceedings of the National Academy of Sciences, the group reports using mathematical models from mortality records to demonstrate how the plague would have spread under different scenarios and what they found by doing so.

Most adults today remember reading in school about the Black Death, which killed approximately 25 million people back in the 1300s, and most also remember being taught that rodents, mostly , spread it around. The was caused by the bacterium Yersinia pestis, which was able to move between victims through various vectors. And until recently, it was believed that fleas that lived on rats jumped from their hosts that died from the plague onto humans, infecting them. But in recent years, that theory has begun to lose credibility because it could not account for how quickly the plague spread, or why there were no reports of of rats from the same disease. In this new effort, the researchers looked at an alternative theory that suggests fleas and lice that lived on humans were behind the spread of the disease.

The team started by amassing data from mortality records regarding the spread of several outbreaks that occurred in Europe between the 14th and 19th centuries (one of which was the Black Death). They then created a that could be used to demonstrate how each of the outbreaks spread. They ran the model under three different scenarios: in which the outbreak was due to rats, airborne transmission, or to human fleas and lice. The researchers found that the scenario in which the outbreak was linked to human fleas and lice offered the best match to what actually occurred. Neither of the other vectors, they found, could cause the disease to spread as quickly as it did. They also note that human fleas and were very common in people during the period under study due to infrequent bathing.

Explore further: Madagascar plague death toll climbs to 30

More information: Katharine R. Dean el al., "Human ectoparasites and the spread of plague in Europe during the Second Pandemic," PNAS (2018). www.pnas.org/cgi/doi/10.1073/pnas.1715640115

Abstract
Plague, caused by the bacterium Yersinia pestis, can spread through human populations by multiple transmission pathways. Today, most human plague cases are bubonic, caused by spillover of infected fleas from rodent epizootics, or pneumonic, caused by inhalation of infectious droplets. However, little is known about the historical spread of plague in Europe during the Second Pandemic (14–19th centuries), including the Black Death, which led to high mortality and recurrent epidemics for hundreds of years. Several studies have suggested that human ectoparasite vectors, such as human fleas (Pulex irritans) or body lice (Pediculus humanus humanus), caused the rapidly spreading epidemics. Here, we describe a compartmental model for plague transmission by a human ectoparasite vector. Using Bayesian inference, we found that this model fits mortality curves from nine outbreaks in Europe better than models for pneumonic or rodent transmission. Our results support that human ectoparasites were primary vectors for plague during the Second Pandemic, including the Black Death (1346–1353), ultimately challenging the assumption that plague in Europe was predominantly spread by rats.

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24volts
5 / 5 (1) Jan 16, 2018
Hmmm, I was taught that it was the fleas on the rats, other animals and people that spread it and not just the rats and that was 45 years ago.... Don't any of these people ever read any old history books?

Turgent
not rated yet Jan 16, 2018
If the vector is flees, lice, and crabs seems plague would have crossed with the Colombian exchange. There appears to be no history of plague decimating indigenous people.
rrwillsj
1 / 5 (1) Jan 16, 2018
Part of the problem with figuring out what actually happened five centuries ago is the lack of reliable records. In addition to such quandaries as, what was a causation in Poland? May not have been the exact same cause in Italy.

The recent article https://phys.org/...mic.html
discusses new evidence that contradicts previous assumptions.

Criticizing previous historical scholars writing about this era with it's multitude of plagues? They did not have the modern technology for accurate analysis and diagnosis.

"Be not too proud of your belief in your absolute mastery of knowledge."

I assure you, that centuries from now? Our descendants will be ridiculing our ignorance and failures to understand reality.
TheGhostofOtto1923
not rated yet Jan 17, 2018
If the vector is flees, lice, and crabs seems plague would have crossed with the Colombian exchange. There appears to be no history of plague decimating indigenous people... In addition to such quandaries as, what was a causation in Poland? May not have been the exact same cause in Italy
The solution to several mysteries regarding the spread of the plague and other diseases in first Europe and then the newly-conquered America's is a singular one. They were spread intentionally.

Marco polo visited the Mongol rulers in China and spent the next 2 years traveling throughout their Empire. Shortly thereafter the plague killed upwards of 200M in Asia.

Mongols delivered it to Europe during their siege of Kaffa. Shortly afterword it began a rapid but inexplicable spread throughout Europe, during a period when these fleas were usually dormant, and mysteriously avoiding certain areas while devastating others.
Cont>
TheGhostofOtto1923
1 / 5 (1) Jan 17, 2018
Priests throughout Europe had perhaps 30x the death rate per capita than the general populace. It it because they were tasked with transporting these flea-infested rodents and infecting the people?

Germ warfare is an ancient art, mentioned many times throughout history. Spartans for instance used it during their siege of Athens. Sun tsu describes in his book how to befoul wells and streams.

And it was the most obvious weapon of choice in conquering the western hemisphere whose inhabitants had no immunity to Eurasian diseases.

This conquest had been planned for centuries. Euros were well aware of the devastating effect on euro markets and society of uncontrolled traffic in drugs and precious metals. They also feared that these commodities would be used to buy western tech, specifically firearms and the tactics to use them effectively.

Europe was first inoculated with these bioweapons and the population allowed to recover. It was then safe to spread them in the americas.
cortezz
5 / 5 (3) Jan 17, 2018
This conquest had been planned for centuries. Euros were well aware of the devastating effect on euro markets and society of uncontrolled traffic in drugs and precious metals. They also feared that these commodities would be used to buy western tech, specifically firearms and the tactics to use them effectively.

You say what? The europeans controlled all import and export of europe so the problem sure was not the uncontrolled traffic of stuff. The Spanish and Portuguese empires took heavy taxes of gold coming from America. Totally not uncontrolled. You think that Europeans somehow feared that the indians would somehow trick the whole market and gather a large arsenal of weaponry? You got any sources for your clames?
Turgent
not rated yet Jan 17, 2018
I can't remember if it was genes or some other marker. In the initial years of HIV some rare individuals infected with HIV were unaffected. There is a link to plague resistance.
rrwillsj
3.7 / 5 (3) Jan 17, 2018
Wow! just Wow!

You guys forgot to blame the millennial spanning, vast international cabals for your ingrown toenail.

"Sometimes a cigar, is just a cigar." An amusing bon mot, No? Yet the ultracrepidarian incomalcons commenting above?

They see a cigar being smoked and describe it as a steam-powered, interstellar zeppelin. Come to take them away for anal probing. A good time was had by all, I'm sure.
TheGhostofOtto1923
not rated yet Jan 17, 2018
europeans controlled all import and export of europe so the problem sure was not the uncontrolled traffic of stuff
BEFORE the conquest the threat was that, because of developing technologies and increased coastal traffic, independent traders could have navigated the atlantic and established their own trade.

Youre aware of the book "1421: The Year China Discovered the World"... the fleets of Chinese Admiral Zheng He visited the Americas prior to European explorer Christopher Columbus in 1492, and that the same fleet circumnavigated the globe a century before..."

-Whether or not this actually happened, it was certainly possible by then.
cont>
TheGhostofOtto1923
not rated yet Jan 17, 2018
The Spanish and Portuguese empires took heavy taxes of gold coming from America
Yeah and they were able to do this because the atlantic was patrolled by euro navies shortly after the invasion, paid for by all the precious metals stolen by conquistadors and shared with the other euro nations via pirate and buccaneer assaults.

It couldnt just be handed out as this would have betrayed the syndicated nature of all the euro dynasties, all related and interbred, and all claiming direct descendence from charlemagne.

The lively interaction of state navies and brigands hired by sovereign countries quickly evolved these navies into unmatched military forces capable of controlling the oceans worldwide.
cont>
TheGhostofOtto1923
not rated yet Jan 17, 2018
Europeans somehow feared that the indians would somehow trick the whole market and gather a large arsenal of weaponry?
The american 'indian' civilizations in the precolombian west had million-man armies, cities bigger than any in europe, and an advanced knowledge of coastal navigation and metallurgy. Further they were bloodthirsty cultures with severe overpopulation problems.

Had they not been quickly and thoroughly destroyed they would have gained knowledge of western tech. Further they had access to all the resources that made the US for instance a world power.

Imagine a huge fleet of aztec or inca slave-powered triremes bristling with bronze cannon, sailing through the gibralter strait, full of armed troops.
You got any sources for your clames?
Yeah my brain.

Official sources quickly obliterated all the cultural records they could find. Out of the 10k mayan books originally found, only 3 remain.

What makes you think they would willingly brag about all this?
TheGhostofOtto1923
not rated yet Jan 17, 2018
One of the most telling things is the route columbus took to get here. He sailed south to the exact latitude that would take him directly into the caribbean. At the time navigators were only able to chart courses east/west.

He knew exactly where he was going and took the most direct route possible to ensure he got there.

Theres lots more. Macchu Picchu was constructed some 60 years before the conquest began. Priests and their families took refuge there and its existence was quickly forgotten. did they know that the invasion was imminent? Were they sent there originally to prepare these cultures for rapid conquest by concentrating all power in the hands of a very few despots?

When montezuma was murdered his empire was immediately commandeered. The inca empire fell within a few decades, aided by 25k miles of paved roads and bridges spanning the empire, built in the decades before the conquest and consuming 60% of incan GDP, also essential for gold collection and transport.
TheGhostofOtto1923
not rated yet Jan 17, 2018
There was so much of this metal that, in order to maintain market value, ships were stuffed full of it and simply scuttled in the atlantic with convincing cover stories as to their fate.
TheGhostofOtto1923
not rated yet Jan 17, 2018
Re biowarfare, the preinvasion mississippian culture had millions of inhabitants, in dozens of cities all along the mississippi, all involved in trade as far away as florida and washington state. The footprint of the pyramid mound at cahokia is actually bigger than the great pyramid at giza. They were only a few gens from a culture rivaling egypt, and their cousins in the south.

This civilization was first recorded by Hernando de Soto's expedition of 1539–1543. When settlers began to arrive some 80 years later this great culture had completely disappeared, ravaged by disease brought by the early explorers.

Had it continued to flourish the rapid spread of western civilization across the northern continent would not have been possible.

Cahokians like the buffalo
https://rarehisto...er-1870/

This is how obsolete cultures have always been disposed of
http://www.histor...er-rouge
TheGhostofOtto1923
not rated yet Jan 17, 2018
Macchu Picchu... Were they sent there originally to prepare these cultures for rapid conquest by concentrating all power in the hands of a very few despots?
Just to be clear, I mean that euro emissaries/priests could have been sent centuries in advance to instruct incipient mesoamerican cultures on how ti deal with the main problem that plagues all civilizations; their malthusian penchant for outgrowing their food supply. These great civilizations around the world all emerged within a few millenia of each other. They all exhibited striking similarities in population control, by constructing great walls or pyramids or massive road and irrigation systems; and by staging ritual warfare, as among the greek city-states.

Not happenstance; diplomacy. An irresistable revelation on how Leaders could establish enduring stability and progress and thereby conquer the world. A WORLDWIDE crime syndicate.

A Tribe of Leaders.
cortezz
5 / 5 (1) Jan 18, 2018
Yeah my brain.

Official sources quickly obliterated all the cultural records they could find. Out of the 10k mayan books originally found, only 3 remain.

What makes you think they would willingly brag about all this?

So, after all the stuff you've thrown againts some pseudoscience guys here, you have the nerves to argument without giving sources? :)

You seem to know much about the subject so please tell more. I have only read history of economics and europe, history of america isn't really my thing. I have never heard that American indians would have used ships to travel outside america nevertheless do trade with ships. Fast googling tells me that they didn't have large ships or any techonology like that. So how do you think they could have done any serious trading by themselves?

The europeans had enormous naval strenght so I think there was no real worries about Americans taking the trade markets. I think it was semi accidental to wipe the civs out.
cortezz
not rated yet Jan 18, 2018
It couldnt just be handed out as this would have betrayed the syndicated nature of all the euro dynasties, all related and interbred, and all claiming direct descendence from charlemagne.

Back then, gold standard was used. Large amounts of gold appearing on the market for free would have crashed the value of all money. I recommend reading Adam Smith's The Wealth of Nations. It really says these things well. So it's not about dynasties and conspiracies. It was to keep trade going.
TheGhostofOtto1923
not rated yet Jan 18, 2018
So, after all the stuff you've thrown againts some pseudoscience guys here, you have the nerves to argument without giving sources? :)
Lots of sources for corroborating evidence, like macchu picchu, incan roads, Columbus path, great civilizations timeline and similarities, Mayan records destruction, etc.

This is not science. Historicity is not falsifiable so I get to interpret events any way I want. And my way makes much more sense than the political propaganda we've been fed.
I have never heard that American indians would have used ships to travel outside america nevertheless do trade with ships
Neither did euros until 1492 and then they were suddenly everywhere. Curiously the date is the same for the expulsion of jews and Saracens from Spain, the obvious jumping point for travel across the atlantic. That occupation, in addition to the brutal dark age inquisition that gripped Europe for centuries, is what had kept heretic and infidel traders out of the atlantic.
TheGhostofOtto1923
not rated yet Jan 18, 2018
Back then, gold standard was used. Large amounts of gold appearing on the market for free would have crashed the value of all money
Exactly. Which is WHY Mesoamerican gold had to be commandeered and controlled by euro dynasties.
The europeans had enormous naval strenght so I think there was no real worries about Americans taking the trade markets
You have cause and effect backwards. Euro ocean-going navies were developed initially to protect new trade routes to the western hemisphere. They didn't exist before the 1500s. They were paid for with captured gold and silver.

If the Mesoamericans had gotten euro tech before then, their capabilities would have quickly surpassed the medieval euros.

Their civilizations were equal or superior to euros in size and available resources. Had they gotten horses, cannon, maritime navigation, and ships, Europe never would have conquered the western hemisphere.
Cont>
TheGhostofOtto1923
not rated yet Jan 18, 2018
Euros struck preemptively. They had no choice. Once they became aware of those civilizations, they knew it was only a matter of time before they were in mortal danger.

Cocaine and tobacco has been found in over 100 Egyptian mummies, leading one to suspect that restricted contact and trade between east and west had gone on for a very long time.

Some speculate that it may actually have been the long way around, via a pacific coastal route along the Canadian coast and the Aleutians. There had been a healthy Indian ocean and southeast Asian coastal trade system for many centuries.

Perhaps this was why the China/mongol dynasties had given up firearms technology, religating it to euros where it could be safely tested and matured in preparation for the transatlantic invasion. They didnt need it to keep their empire under control, and the danger that the mesoamericans could have gotten hold of it was just too great.
TheGhostofOtto1923
not rated yet Jan 18, 2018
Columbus headed straight for the Caribbean because Cuba and Hispaniola were ideal staging points for the invasion. It was launched from the Iberian peninsula because again, this offered the most direct route across the Atlantic as well as providing the most easily controlled repository for all the gold and silver brought back.

But Spain did not act alone. As events developed it became clear that all the euro countries/dynasties were working to conquer and settle both continents according to a predetermined plan.

The fact that the euro/Moslem conflict ended at the exact moment this invasion was launched also lends one to believe that a worldwide coordinated effort to conquer the world had entered a final and crucial stage.
billpress11
not rated yet Jan 18, 2018
Quote Ghost:
"One of the most telling things is the route columbus took to get here. He sailed south to the exact latitude that would take him directly into the caribbean. At the time navigators were only able to chart courses east/west."

You certainly know more about this than I do, but I never heard about the native Americans having any sort of naval force. Also I think you may be reading more into this than there is about the route Columbus took to get to America. Portuguese sailors had traveled down the west coast of Africa for decades before Columbus set sail. Almost certainly he was aware of the westward winds at that latitude. These westerly winds made it possible for him to get to the Caribbean Sea.

https://en.wikipe...–1578)
Treaty of Tordesillas
cortezz
not rated yet Jan 18, 2018
Yes, I agree with Otto on the points that they were advanced civs with possibly large armies but I don't believe they had intent to start large scale sailing or trading by sea. I don't believe Europeans thought that as a threat either. Didn't the American people welcome Europeans with open arms? Handing out free gold etc? Why would they be considered a huge threat. I think it's more like "These people are wealthy and stupid, lets take advantage of that". Then it just happenned to be so that they didn't have defence againts our diseases which led to total wipe out which was not necessarily intended.
TheGhostofOtto1923
not rated yet Jan 18, 2018
I never heard about the native Americans having any sort of naval force
"Maritime trade in the Maya civilization
From Wikipedia, the free encyclopedia

Maritime Trade Goods of the Maya
The extensive trade networks of the Ancient Maya contributed largely to the success of their civilization spanning three millennia. The Maya royals control and wide distribution of foreign and domestic commodities for both population sustenance and social affluence are hallmarks of the Maya visible throughout much of the iconography found in the archaeological record. In particular, moderately long distance trade of foreign commodities from the Caribbean and Gulf Coasts provided the larger inland Maya cities with the resources they needed to sustain settled population levels in the several thousands."

-In order to KNOW something you have to LOOK.
These westerly winds made it possible for him to get to the Caribbean Sea
Yeah, so?
TheGhostofOtto1923
not rated yet Jan 18, 2018
they had intent to start large scale sailing or trading by seathey had intent to start large scale sailing or trading by sea
And if they had known of europe, and had become aware pf the markets there, and of the value of their metals and drugs, do you think then they may have had somewhere to go?

But they really didnt have to go anywhere. Euro traders would have traded euro tech, weapons, horses, war dogs, etc for mesoamerican commodities. Euro markets would have then collapsed as the value of royal treasuries plummeted.

The more gold in circulation, the less it is worth.
Didn't the American people welcome Europeans with open arms?
They slaughtered viking settlers to a man. Early euro settlements were similarly destroyed.
TheGhostofOtto1923
not rated yet Jan 18, 2018
"The Spanish conquest of the Inca Empire was one of the most important campaigns in the Spanish colonization of the Americas. After years of preliminary exploration and military skirmishes, 180 Spanish soldiers under conquistador Francisco Pizarro, his brothers, and their native allies captured the Sapa Inca Atahualpa in the 1532 Battle of Cajamarca. It was the first step in a long campaign that took decades of fighting but ended in Spanish victory in 1572"

-And consider how long it took to subdue amerinds across north america once they got guns and horses. No 'open arms'.
it just happened to be so that they didn't have defence againts our diseases which led to total wipe out which was not necessarily intended
Of course total cultural annihilation was the intent. I have told you why. American commodities and cultures were a critical threat to europe and the rest of the world.

The weapons of choice were germs, spread by intent. And they worked spectacularly well.
leetennant
not rated yet Jan 18, 2018
The rodents were responsible only because they carried the fleas. Wasn't this common knowledge?
TheGhostofOtto1923
not rated yet Jan 18, 2018
I never heard about the native Americans having any sort of naval force
Euros didnt have navies either until they had something to protect. Like I said.

Aztec naval forces described here.
https://books.goo...;f=false

"When the Aztecs feigned a withdrawal, Cortés pursued them across an unfilled breach, upon which the Aztecs cut him off by sending war canoes into the breach, catching him between their land and their naval forces. Cortés escaped, wounded, but many others did not, including sixty-eight Spaniards and eight horses that ..." etc
StudentofSpiritualTeaching
1 / 5 (1) Jan 20, 2018
You might want to read the transcript of this interesting conversation from 1981:
http://www.future...port_148
We read nothing less than a claim that the long-standing bad practice of keeping dogs and cats around has historically been responsible for 59% of deaths from plague.

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