The Black Death

Causes and Symptoms of the Bubonic Plague

The Black Death strikes Italy
The Black Death strikes Italy. Detail of Luigi Sabatelli's 19th-century etching. "The plague of Florence in 1348," as described in Boccaccio's Il Decameron.. Made available by the Wellcome Library through the Creative Commons Attribution 4.0 International license

The Black Death, also known as The Plague, was a pandemic affecting most of Europe and large swaths of Asia from 1346 through 1353 that wiped out between 100 and 200 million people in just a few short years. Caused by the bacterium Yersinia pestis, which is often carried by fleas found on rodents, the plague was a lethal disease that often carried with it symptoms like vomiting, pus-filled boils and tumors, and blackened, dead skin.

The plague was first introduced in Europe by the sea in 1347 after a ship returned from a voyage across the Black Sea with its entire crew either dead, ill or overcome with fever and not able to eat food. Due to its high rate of transmission, either through direct contact with fleas carrying the bacterium or via airborne pathogens, the quality of life in Europe during the 14th century, and the dense population of urban areas, the Black Plague was able to quickly spread and decimated between 30 to 60 percent of the total population of Europe.

The plague made several reemergences around the world throughout the 14th through 19th centuries, but innovations in modern medicine, combined with higher standards of hygiene and stronger methods of disease prevention and epidemic outbreak mitigations, have all but eliminated this medieval disease from the planet.

The Four Main Types of Plague

There were many manifestations of the Black Death in Eurasia during the 14th century, but four main symptomatic forms of the plague emerged at the forefront of historical records: the Bubonic Plague, the Pneumonic Plague, the Septicemic Plague, and the Enteric Plague.

One of the symptoms most commonly associated with the disease, the large pus-filled swellings called buboes, give the first type of plague its name, the  Bubonic Plague, and was most often caused by flea bites filling with infected blood, which would then burst and further spread the disease to anyone who came in contact with the infected pus.

Victims of the Pneumonic Plague, on the other hand, had no buboes but suffered severe chest pains, heavily sweated, and cough up infected blood, which could release airborne pathogens that would infect anyone nearby. Virtually no one survived the pneumonic form of the Black Death.

The third manifestation of the Black Death was Septicemic Plague, which would occur when the contagion poisoned the victim's bloodstream, almost instantly killing the victim before any notable symptoms had a chance to develop. Another form, Enteric Plague, attacked the victim's digestive system, but it too killed the patient too swiftly for diagnosis of any kind, especially because Medieval Europeans had no way of knowing any of this as the causes of plague were not discovered until the late nineteenth century.

Symptoms of Black Plague

This contagious disease caused chills, aches, vomiting and even death amongst the healthiest people in a matter of a few days, and depends on which type of plague the victim contracted from the bacillus germ Yerina pestis, symptoms varied from pus-filled buboes to blood-filled coughing.

For those who lived long enough to exhibit symptoms, most victims of the plague initially experienced headaches that quickly turned into chills, fevers, and eventually exhaustion, and many also experienced nausea, vomiting, back pain, and soreness in their arms and legs, as well as all-over fatigue and general lethargy.

Often, swellings would appear which consisted of hard, painful, and burning lumps on the neck, under the arms, and on inner thighs. Soon, these swellings grew to the size of an orange and turned black, split open, and began to ooze pus and blood.

Lumps and swellings would cause internal bleeding, which led to blood in the urine, blood in the stool, and blood puddling under the skin, which resulted in black boils and spots all over the body. Everything that came out of the body smelled revolting, and people would suffer great pain before death, which could come as quickly as a week after contracting the disease.

The Transmission of Plague

As mentioned above, the plague is caused by the bacillus germ Yersinia pestis, which is often carried by the fleas that live on rodents like rats and squirrels and can be transmitted to humans in a number of different ways, each of which creates a different type of plague.

The most common way the plague spread in 14th-century Europe was through flea bites because fleas were such a part of everyday life that nobody really noticed them until it was too late. These fleas, having ingested plague-infected blood from their hosts would often attempt to feed on other victims, invariably injecting some of the infected blood into its new host, resulting in the Bubonic Plague.

Once humans contracted the disease, it further spread through airborne pathogens when victims would cough or breathe in close quarters of the healthy. Those who contracted the disease through these pathogens fell victim to the pneumonic plague, which caused their lungs to bleed and eventually resulted in a painful death.

The plague was also occasionally transmitted by direct contact with a carrier through open sores or cuts, which transferred the disease directly into the bloodstream. This could result in any form of the plague except pneumonic, although it is likely that such incidents most often resulted in the septicemic variety. The septicemic and enteric forms of the plague killed the quickest of all and probably accounted for the stories of individuals going to bed apparently healthy and never waking up.

Preventing the Spread: Surviving the Plague

In Medieval times, people died so swiftly and in such high numbers that burial pits were dug, filled to overflowing, and abandoned; bodies, sometimes still living, were shut up in houses which were then burned to the ground, and corpses were left where they died in the streets, all of which only further spread the disease through airborne pathogens.

In order to survive, Europeans, Russians, and Middle Easterners eventually had to quarantine themselves away from the sick, develop better hygiene habits, and even migrate to new locations to escape the ravages of the plague, which tapered off in the late 1350s largely because of these new methods for disease control.

Many practices developed during this time to prevent further spread of the disease including tightly folding clean clothes and storing them in cedar chests far from animals and vermin, killing and burning the corpses of rats in the area, using mint or pennyroyal oils on the skin to discourage flea bites, and keeping fires burning in the home to ward off airborne bacillus.

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Team, ThoughtCo. "The Black Death." ThoughtCo, Dec. 6, 2021, Team, ThoughtCo. (2021, December 6). The Black Death. Retrieved from Team, ThoughtCo. "The Black Death." ThoughtCo. (accessed March 28, 2023).