How Did the Black Death End?

The first wave burned out in about four years. The pandemic behind it took another three and a half centuries.

The Black Death did not end so much as subside, and then keep coming back. The first and worst wave swept Europe between 1347 and 1351 and burned itself out within a few years in any given region, largely because it had killed or exposed so much of the population that it ran short of new hosts. But the pandemic it belonged to, usually called the second plague pandemic, continued for more than three centuries, with major recurrences including the Great Plague of London in 1665 and the Great Plague of Marseille in 1720, which was the last major outbreak of bubonic plague in western Europe.

The disease was caused by the bacterium Yersinia pestis, spread mainly by fleas, and also transmissible through contact with infected tissue and, in the pneumonic form, directly between people through respiratory droplets. Estimates of the first wave's toll run from 25 to 50 million people, or somewhere between 30 and 60 percent of Europe's population, with comparable devastation across the Middle East and North Africa. Plague was present somewhere in Europe in every single year between 1346 and 1671.

So the honest answer to 'how did it end' has three parts. The first wave ended for the ordinary epidemiological reason that epidemics end: susceptible people ran out. The recurrences were gradually contained by human action, above all quarantine, cordons, and port controls, which is where the practice and the word both come from. And the disease itself never ended at all. Plague still circulates in rodent populations on several continents and still infects people, at a rate of roughly 600 reported cases a year worldwide.

Why the first wave stopped, 1347 to 1351

The chronology of the first wave is unusually well documented. Plague reached Constantinople in the summer of 1347 and Sicily in October of that year. By June 1348 it was in France, Spain, Portugal, and England. It moved through Germany, Scotland, and Scandinavia across 1348 to 1350, and reached Moscow by 1353. In most localities the acute phase lasted months rather than years, and then the dying stopped almost as abruptly as it had begun.

The main reason is grim arithmetic. An outbreak that kills or exposes a very large fraction of a town's population in a single season exhausts its own fuel. With fewer susceptible people packed together, chains of transmission break. Seasonality helped too, since flea activity falls in cold weather, which is why many outbreaks eased in winter and resumed in the warmer months.

Human behaviour contributed, though rarely in the ways contemporaries intended. People fled infected towns, which sometimes spread the disease further but also thinned the dense urban populations that sustained it. Trade collapsed in affected regions, which slowed the movement of goods, rats, and fleas. What did not work was almost everything medieval medicine actually prescribed, from bloodletting to aromatic remedies, and the persecution of Jewish communities that accompanied the plague in parts of Europe was both an atrocity and epidemiologically irrelevant.

It is worth being clear that survivors did not become immune in any lasting collective sense. Later waves killed again, including children born after the first wave who had no exposure at all. Some researchers have argued for genetic selection favouring resistance in survivor populations, and there is active work on this, but it is not a settled explanation for anything and should not be presented as one.

Quarantine, invented in response

The single most important institutional response to plague was the invention of quarantine, and it is a direct product of this pandemic. In 1377 the city-state of Ragusa, modern Dubrovnik in Croatia, required arrivals from plague-affected places to spend thirty days in a restricted location before entering the city. The Italian word for a thirty-day period, trentino, gave the practice its first name.

Venice built on the idea, establishing an isolation hospital on an island beside the city in the early fifteenth century, and the isolation period was eventually extended from thirty to forty days. The Italian for forty days, quarantena, is where the English word quarantine comes from. Whether forty days was chosen for medical or religious reasons is debated, but the effect was to hold ships and travellers long enough for an infection to declare itself.

What makes this remarkable is that it worked without any correct understanding of why. Nobody in 1377 knew about bacteria, and the flea was not identified as a vector until the very end of the nineteenth century. The Ragusan and Venetian authorities were acting on an observation, that plague travelled with people and goods from certain places, and they built policy on it. Over the following centuries Mediterranean states developed an increasingly professional apparatus of health boards, bills of health, lazarettos, and land cordons.

By the eighteenth century that apparatus was effective enough to matter. When plague broke out in Marseille in 1720, after the merchant ship Grand-Saint-Antoine arrived from the Levant, the outbreak killed roughly 50,000 people in the city out of a population of about 90,000, and around 100,000 in total across the surrounding region. It was a catastrophe. But it was contained to Provence rather than spreading across the continent, and it was the last major bubonic plague outbreak in western Europe.

Why plague faded from Europe, and what we do not know

The disappearance of plague from western Europe after 1720 is one of the genuinely open questions in the history of disease, and anyone who gives you a single confident cause is overselling. Several explanations are in play, and they are not mutually exclusive.

Quarantine and cordon systems are the most concrete. The Habsburg military frontier maintained a permanent cordon against plague from the Ottoman lands, and Mediterranean ports operated increasingly rigorous inspection regimes. The Marseille outbreak itself is usually read as a failure of controls that otherwise held, which is an argument that the controls were doing real work.

Changes in the built environment are often cited. Brick and stone construction, tiled rather than thatched roofs, and better-separated living and storage space made buildings less hospitable to commensal rodents. Rising living standards, more soap, and more washable linen changed the flea's opportunities. None of these is easy to quantify at a European scale, and the timing is uneven.

Ecological explanations concern the pathogen and its animal hosts rather than people. Shifts in the rodent populations that carry plague, in the flea species involved, or in the bacterium itself could all alter how readily human epidemics ignite. Genetic work on Yersinia pestis recovered from medieval burials has confirmed the pathogen's identity and traced its lineages, but it has not produced a clean answer to why European epidemics stopped.

One explanation you can safely discard is that plague was cured. There was no treatment worth the name until antibiotics arrived in the twentieth century, roughly 220 years after Marseille. Whatever ended European plague, it was not medicine.

Plague today

Yersinia pestis was never eradicated. It persists in wild rodent populations across parts of Africa, Asia, and the Americas, and spills over into humans regularly. Around 600 cases are reported globally each year, with the highest incidence in the Democratic Republic of the Congo, Madagascar, and Peru. In the United States a handful of cases occur most years in rural western states where the bacterium circulates among ground squirrels, prairie dogs, and their fleas.

The disease takes three forms. Bubonic plague, the classic form, swells the lymph nodes into the painful buboes that gave the disease its name. Septicaemic plague infects the bloodstream. Pneumonic plague infects the lungs and is the only form that spreads directly from person to person through the air, and it is by far the most dangerous, capable of killing within days if untreated.

The difference between then and now is treatment. Plague responds well to antibiotics, with gentamicin and fluoroquinolones among the standard drugs, and prompt treatment brings mortality down to around 10 percent against roughly 70 percent untreated. The limiting factor is speed of diagnosis, which is why the cases that still prove fatal are usually the ones nobody recognised in time.

That is the real shape of the answer. The Black Death, meaning the specific catastrophe of 1347 to 1351, ended when it ran out of people to kill. The pandemic ended in Europe gradually and for reasons still argued over, with quarantine doing more than medicine. The organism has not ended at all. It simply stopped being able to do to us what it once did.

Frequently asked questions

How did the Black Death end?

It did not end cleanly. The first wave of 1347 to 1351 subsided within a few years in each region, mainly because it had killed or exposed so much of the population that transmission chains broke. But plague returned repeatedly for more than three centuries, and was present somewhere in Europe every year between 1346 and 1671. The last major western European outbreak was at Marseille in 1720.

What caused the Black Death?

The bacterium Yersinia pestis, spread mainly by fleas, and also transmissible through contact with infected tissue or fluids. In its pneumonic form it spreads directly between people through respiratory droplets. The pathogen's identity has been confirmed by genetic work on remains from medieval plague burials.

Did quarantine stop the plague?

It helped, and it was invented for this purpose. Ragusa, modern Dubrovnik, imposed a thirty-day isolation on arrivals from infected places in 1377, and Venice later built isolation hospitals and extended the period to forty days, which is where the word quarantine comes from. These measures worked without any correct understanding of the cause, and by the eighteenth century port controls and land cordons were containing outbreaks rather than merely recording them.

Why did plague disappear from Europe?

Historians do not agree. The leading candidates are increasingly effective quarantine and cordon systems, changes in housing and hygiene that reduced contact with rodents and fleas, and ecological shifts in the animal hosts or in the bacterium itself. It was certainly not medicine, since no effective treatment existed until antibiotics arrived roughly 220 years after the Marseille outbreak of 1720.

Does the plague still exist today?

Yes. Yersinia pestis persists in wild rodent populations on several continents, and about 600 human cases are reported worldwide each year, with the highest numbers in the Democratic Republic of the Congo, Madagascar, and Peru. It responds well to antibiotics when caught early, which brings mortality down to around 10 percent compared with roughly 70 percent untreated.

Further reading

Prefer listening? History is Audible’s strongest catalog — an annual Premium Plus membership is the best value, or compare the monthly plans.

Related guides

• How Many People Died in the Black Death?
• Best Books on Medieval History
• Were the Dark Ages Really Dark?

Sources consulted

• Wikipedia, 'Black Death'
• Wikipedia, 'Great Plague of Marseille'
• Wikipedia, 'Plague (disease)'
• Open Library record: Ole J. Benedictow, The Black Death 1346-1353

Researched with AI and verified against mainstream scholarship and the cited sources on this page. See our methodology and corrections policy.

As an Amazon Associate, AskHistoryAI earns from qualifying purchases. Books are chosen editorially.