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Black Death: the course of the disease in seven days

Nothing in human history has decimated the world’s population so efficiently and in such large numbers as the dreaded Black Death. No war, disease or genocide had ever been as effective and successful as this disease, which single-handedly killed the world by 75 to a hundred million people.


The Black Death was an epidemic of unprecedented destructive power that wreaked havoc across the world in the fourteenth century. In the Middle East and Europe, this epidemic has killed about a third of the total population there, whether they were men, women, children, or even clergy. Contrary to long believed, the victim is not infected by a virus, but by a bacterium, ‘Yersinia pestis’ , which is transmitted by fleas. It is often thought that rats were responsible for the direct spread of the bacteria, but in fact these mainly black rats were only the carriers of the real vectors, the fleas. The rats were indeed the carriers of the bacteria, but the infection on humans was mainly caused by fleas.


In contrast to modern society where people shower or bathe on average three to four times a week, people in the Middle Ages were not very interested in hygiene. People hardly washed themselves, only cleaned their house a little from time to time and they certainly did nothing about those rats and fleas. It was very normal during that period that rats walked through the streets and no one was surprised if you had fleas, that was just part of life. These infected fleas could easily transmit the bacteria, because they simply jumped around among people, who lived very close together, especially in the cities.


The ‘Yersinia pestis’ was an inventive bacterium. First, the rats were infected, and they died in droves. That didn’t really seem like a disaster to anyone at the time, because one less rat is just a bonus. These rats, however, had annoying visitors, the flea, which was undoubtedly the most common pet of humans without them even realizing it. When these fleas drank blood from the rats, the flea was infected by the bacteria in the blood and now became a flea infected with the Black Death. The bacterium ingeniously clogged the flea’s stomach entrance, so that it constantly felt hungry. The result of this is that the fleas start biting all around them to get that blood. Once the rats have all died, they start looking for other prey, including humans. Because almost everyone had fleas at the time, the flea and thus the plague bacteria could spread very quickly.

An average week with the Black Death

Of course, some victims lasted a little longer than others, but in general it was over after a week for most. Seven days was all it took for the bacteria to destroy a person from the inside out.

Day 1

The first day after the bacteria entered the body, the symptoms were not very serious. This day was characterized by symptoms that were common when you had a bit of flu, such as headache, chills and fever. Because these were common symptoms, the population at the beginning of the epidemic did not realize that these were the symptoms of a deadly bacteria.

Day 2

The symptoms of the second day could also be attributed to a persistent flu. Nausea and vomiting were prevalent this second day after infection.

Day 3

From day three the limbs started to hurt. An indeterminate kind of pain ran through the arms and legs and this was one of the first symptoms that could really be distinguished from normal flu.

Day 4

A characteristic symptom of the plague and especially of the bubonic plague were the swellings of the lymph nodes in the neck, limbs, armpits and groin. This is where the bubonic plague gets its name. As the bumps grow, they become more and more painful and sensitive, causing the victim to hardly dare to move. The tissue around the swollen lymph node also begins to become inflamed, becomes sensitive and turns red.

Day 5

The constantly growing bumps can no longer handle the pressure and burst open, exuding a lot of blood and pus. This was not a pleasant sight for their caretakers and the stench was terrible.

Day 6

The ‘Yersinia pestis’ destroys the body from the inside and internal bleeding starts on day six. If the plague is not treated quickly, the infection will spread throughout the body via the bloodstream. This is called the septic plague. The blood clots, internal bleeding occurs and this means that vital organs do not receive enough blood and oxygen, so that they can no longer function properly and subsequently fail completely.

Day 7

The victim dies from complications of the plague.

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