The Real (and Perceived) Cause of the Black Plague: Part 1

This week is plague week at Retrospectacle, and every day I will be posting something about the Black Plague.

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The Black Plague was responsible for wiping out 1/3 of the population of Europe during the 1300s, and is considered one of the worst (is not THE worst) pandemic in recorded history. The plague was particularly feared due to its high infectiveness, low chance for survival, and ability to wipe out entire villages in a matter of weeks. Once infected, a patient died in a matter of days amidst much agony. The names for the Black Plague (in the 1300s) included the "Great Pestilence," the "Great Death," and the "Great Plague." The terms "Black Plague" and "Black Death" were used for the first time in the 19th century.

During the worst outbreak in the 1300s, doctors were afraid to treat it, few scientists studied it and lived to report their findings. With no cure in sight, authorities relied on containing it best they could. Methods varied from housing victims together in 'pest houses' to locking people in their houses and waiting for them to die. Not that there wasn't plenty of speculation on the causes of the plague.

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Various theories as to the origins of the plague abounded. At first, livestock or natural disasters were blamed for outbreaks, but as the amount of human misery became staggering, divine causes became popular. The pious believed that the Plague was punishment from God, sent to purge sinners and leave the innocent untouched. This unfortunately led to attacks on Jews, and in 1349 entire communities in Mainz and Cologne were exterminated, as well as 2,000 Jews in Strasbourg. Lepers and other people suffering from an obvious malady were also targeted, and other minority groups like foreigners, gypsies, and beggars were also singled out. In Egypt, women were blamed after religious lawyers informed the sultan that the plague was a result of God's displeasure with rampant fornication. This led to women being unable to appear in public, lest they tempt men.

The route of transmission was another mystery. One theory was that 'bad air' or 'miasmas' were responsible, which led to people trying to sniff herbs or smelling salts to purge their air. The Catholic Church could neither explain nor cure the pestilence, and lost much credibility as a result (although some people did take to flagellating themselves as a penance to avoid the plague). The consumption of alcohol rose dramatically during the Plague (for various reasons) and was considered a remedy, as was coffee. The gemstone citrine was also considered a talisman to ward off the Plague, also ineffectual. While tens of thousands of cats and dogs were culled, no one thought that controlling the rat population might reduce infection.

It wasn't until the end of the 19th century, in 1894, that the infectious organism responsible for the Plague was identified. Two research teams - one led by the Japanese scientist Shibasaburo Kitasato and the other by the Frenchman Alexandre Yersin, a former pupil of Louis Pasteur - simultaneously isolated the bacillus Pasteurella pestis (now called Yersinia pestis, picture at right) that is thought to be responsible for the Plague. It was a disease of rodents and was spread by their fleas. As the rats died, the fleas would frantically look for new hosts, jumping on human beings. Later experiments illustrated how virulent the Plague really was: mice died after being infected with just three bacilli, and fleas can disgorge up to 24,000 in one bite.

Three main 'types' of Plague were then identified-- bubonic, septicaemic, and pneumonic--which varied by the entrance of the infection. Bubonic plague entered a human via the lymph system and was characterized by 'buboes' (swelling of lymph nodes). Septicaemic plague resulted when the bacillus entered the bloodstream directly, and was almost always fatal. Pneumonic plague was the most deadly, and could be acquired without a flea-bite, by breathing the bacillus into the lungs.

There is some recent controversy that Pasteurella pestis is not the actual bacillus involved in the Black Plague. But, you'll have to wait until Part 2 to hear about it!


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From the etiquette of thank you notes to videos of human brain surgery and now plaque week??? I have no idea how your mind works, Shelley, but it is interesting and entertaining to watch its twists and turns!

I'm still reeling from the fish head thing.

From the fleas of rats and mouses
To a plague a' both your houses,
If we can't blame sheep or horses, then we gotta blame the Jews
When we found a small bacillus,
Not a god, had tried to kill us
It's the sort of information anyone can surely use!
If you wish Yersinia pestis
Not to kill you, our request is
That you clean the fleas from bedding, and the rats from in your larder
But if you're afraid of science
And you'd rather put reliance
In the methods of the church, then their advice is: Just pray harder!

So, what does it mean that the leader of the largest church today's nickname is Joey Ratz?

I think it is a sign from above that in order to save the world, everyone needs to become an atheist ASAP.

But seriously, looking forward to Part 2.

You are so wrong, you're not even right. Everyone who's anyone knows that Shakespeare caused it all with loose talk in Romeo and Juliet (aka "Ethel the Pirate's daughter")....

The Pied Piper story is supposed to contain a folk memory of the Black Death ... first the rats disappear, then the children ... the colours of the piper are the colours of the swellings associated with the disease.

Another folk memory is the children's game and rhyme "Ring-a-ring o' rosies, bottle full of posies, Acha, Acha, we all fall down" ... the "ring o'rosies" are the buboes, the "bottle full of posies" are the scents people carried to ward off the "miasmas", the "Acha" represents sneezing (?) and you can get the "all fall down".

The Black Death had a profound influence on Europe. for example, a shortage of labour meant that sefs had much better bargaining power to claim ownership over land. In the chaos many broke free from their feudal lords, heralding a much looser social order.

I did see a documentary a couple of years ago, contending that Bubonic Plague was probably not the cause of the Black Death. I know that in the past some have claimed anthrax as the cause, but this film offered evidence for an unknown respitory ailment. Cue fear of a bird flu epidemic etc.

Great post, very interested in Part II. One little 'nit' - coffee was not introduced to Europe until after the discovery of America. It probably only became a "cure" for later plagues like the one in England in the 1660s, not the Great Pestilence of the 14th century.

With the lack of structured communication and epidemiologists, how long did it take for Europe to notice it had a problem?

The idea that ring-a-ring o rosies relates to the Black Death is a popular one but has been rather thoroughly debunked. for example.

The anthrax theory is Norman Cantor's. He offers nothing remotely like evidence for it, it's just controversialism on his part I think.

While we're picking on Toby, it does seem rather odd that coffee would not have been introduced to Europe until after the discovery of America, given that coffee is an African plant, first made into a beverage by Arabs. Hmmm... was there any contact between Europeans and Arabs during the middle ages? One supposes that this is the sort of thing one could look up, if one were the sort of person who did that sort of thing.

Shelley, here's a literary contribution to plague week: King Pest, by Edgar Allan Poe. Set during the Black Plague, this is an extremely bizaare little tale -- half horror story, half comedy, half political satire, and half psychedelic fever-dream.

I model plague dynamics in prairie dogs... little buggers get wiped out like crazy, especially during El Nino years. It's good to see plague getting some press, most of the people I talk to are pretty clueless ("Isn't it still a mystery what caused the Black Death?" "No. Not really." "Oh, I heard it was a mystery. I guess we'll never know." "No, we know. Pretty definitively." "Never know...")

Can't wait to see if I actually have anything to contribute in the coming posts. :P

Feeling thoroughly humbled over the ring-o'-rosie. Can't really complain, I just love debunking when I see the opportunity. The new knowledge is worth the pain,

Better go and check out coffee!! Certainly, coffee only became a drink of the European middle classes in the 17th century, when the first coffee houses started to open in large numbers. Were coffee beans used by medieval apothecaries as "cures"?

Wow...I stumbled on your blog whilst searching for ear infection info...liked what I read... And then thought to read your latest post and it's on the Black Plague! I find this an odd coincidence, because I have been reading Barbara Tuchman's "A Distant Mirror: The Calamitous 14th Century" during my recent ear infection recovery period. Assuming you have read's a whallop of a book. The 14th century in Europe was quite cursed. I look forward to your future postings for "plague week," as i recover from this blasted ear thing. I wish you well!

By Graciepoo (not verified) on 08 Jan 2008 #permalink

Just came back to read Retrospectacle after 2+ weeks not visiting, and you torment me with part 1? Gah! Please, part 2 soon. One of the most interesting things I've had the pleasure of reading lately. Certainly much higher value than most of the gaming and geek reading I typically consume.

Is it can be plague: part 2 time? Please? :)

Part 2 is coming out tonight! I was in lab laaaaate last night and had no blog-time, so I'll have to write it and post it tonight. Don't worry, its coming! :)

Coffee wasn't known as a beverage anywhere before the 16th century. It spread around the middle east (Turkish empire) through the 1500s and only arrived in western Europe in the 1650s. Mediaeval apothecaries would have never heard of the stuff (even in Alexandria).