Finally — for many of them — came death.
Today, many of us think of the plague as something confined to the history books — a grim symbol of the medieval period, before doctors knew about the existence of viruses or bacteria.
Neither is debate about the cause of the disease, how it spread, and even where it came from.
Plagued by questions
For a disease that has impacted humans for centuries, there’s still plenty we don’t know about the plague.
But starting in the 1970s and 1980s, historians and biologists began pointing out that the second pandemic didn’t act like the third pandemic in a significant way: it killed many more people. That prompted people to posit that another disease had caused the Black Death, said historian Winston Black, who is writing a book that busts a number of plague theories.
“They’re often called the ‘plague deniers’ — they’re denying that the medieval Black Death was the bubonic plague,” Black said. “They’ve proposed anthrax, (and) something like an early Ebola.”
The turning point came in the 2000s, when scientists developed the ability to extract ancient DNA — including from medieval skeletons.
When scientists analyzed the skeletons of plague victims, they found fragments of Yersinia pestis, said Black. But that only led to another question: if the disease wasn’t genetically different, then why was the second pandemic so deadly?
In the past, that’s been attributed to the poor hygiene and close living quarters of people during the medieval period. But Black says that still doesn’t completely explain it, as others have lived in similarly bad conditions and not experienced such a rapid and deadly plague.
And there are other questions and misconceptions that remain over the Black Death.
Although the nursery rhyme “Ring Around the Rosie” is widely thought to be about the plague, Black said that was an incorrect theory created decades after the song was first sung. And the popular notion that doctors wore beaks — supposedly to protect them from infection — during the Black Death was also wrong, Black said — the mask wasn’t invented for hundreds of years after the second pandemic.
And the idea that the second pandemic, the Black Death, could have started in China is unlikely, Black said.
DNA evidence extracted from the skeletons of medieval plague victims, and genetic analysis of the bacteria, suggest that the outbreak probably originated in central Asia, and moved east into China, and west into Europe via trade routes, said Black.
Even if the second pandemic had come from China, the Zheng He theory isn’t feasible — as Black points out, if Zheng He’s ship was carrying plague-infested rats, the whole crew would most likely be dead before they reached Africa.
China’s brush with modern plague
That bubonic plague outbreak made its way to Hong Kong — then a British colony — and from there, spread via trade routes to other parts of Asia and the United States.
“It’s undeniable that there was this pathway of transmission from China to the outside world,” said Jack Greatrex, who is working on a PhD at Hong Kong University about the history of the plague in Hong Kong.
That outbreak sparked the third global plague pandemic. But it was another plague outbreak that would help shape China’s future.
At the time, parts of China were occupied by foreign powers. Both the Russian and Japanese empires claimed they could manage the plague in Manchuria better than China, which showed China that disease could be a “security disaster” as it “legitimated colonial meddling,” said Miriam Gross, who studies public health in China and is a professor at the University of Oklahoma.
When the founder of modern China, Mao Zedong, came to power in 1949, he made disease control a priority. There were a number of reasons for that, but one was to show that China could handle its own affairs and didn’t need outside help, Gross said.
So Mao put in place a number of measures to control the country’s rampant disease. One of his most famous and unusual proposals was the “Four Pests Campaign,” where Mao called for rats, flies, mosquitoes and sparrows to be eliminated. The rats were to be killed to control schistosomiasis, which is sometimes translated in English as “plague” although it is a different disease.
But the Four Pests Campaign led to the slaughter of millions of wildlife, which disrupted the country’s ecology and contributed to a mass famine during which millions of people died.
Why we’re so fascinated by the plague
Centuries on from the Black Death, people around the world continue to be transfixed by the plague in a way they’re not by other diseases.
But even if the disease isn’t a major threat for most countries, it still interests scientists and historians, who are continuing to make discoveries about the Black Death, despite it occurring hundreds of years ago.
Greatrex, from Hong Kong University, said the plague continued to be haunted by its history. “You hear of the plague, and instantly you think of Black Death which ravages Europe, it has that enormous historical baggage,” he said. “It’s where lots of our ideas about what it means to have an epidemic comes from.”
Black, the historian, said the fascination with the Black Death comes from a deep cultural memory in the Middle East and Europe, where the disease was written about for centuries.
However, he said other diseases — such as malaria and Ebola — should be of greater concern.
“It’s so central to Western identity,” he said. “It’s part of our past, where something like malaria, which is so much more devastating in the last century, it doesn’t interest us.”