Scientists SOLVE the mystery of the Black Death's prolonged reign of terror - as they pinpoint a single gene that allowed it to endure across centuries

Daily Mail​

30-05-2025

The Black Death remains the single deadliest pandemic in recorded human history.
The deveastating pandemic wiped out up to half of the populations of Europe, Western Asia and Africa, killing tens of millions of people.
Now, the mystery of the Black Death's prolonged reign of terror has finally been solved.
Research has revealed that the evolution of a single gene in Yersinia pestis - the bacterium that causes bubonic plague - allowed it to adapt and survive for so long.
The study addresses key questions about how pandemics enter human populations, cause immense sickness, and evolve different levels of virulence.
And in the future, the findings could help us to pre-empt another pandemic.
'This is one of the first research studies to directly examine changes in an ancient pathogen, one we still see today, in an attempt to understand what drives the virulence, persistence and/or eventual extinction of pandemics,' said co-senior author Professor Hendrik Poinar.
The new study was conducted by researchers at McMaster University in Canada and France's Institut Pasteur.
The bacteria that cause the plague evolved to become less deadly over time, allowing it to continue infecting people in three separate pandemics over more than a thousand years, their research revealed.
The first pandemic - the plague of Justinian - struck in the 500s at the start of the Middle Ages and lasted for around 200 years.
The Black Death began in the mid-1300s and would become the deadliest pandemic in human history, killing up to half of the people in Europe, western Asia and Africa, with outbreaks continuing for centuries.
The third bubonic plague pandemic broke out in China in the 1850s and continues today, with some cases still being recorded in parts of sub-Saharan Africa.
'The plague bacteria have a particular importance in the history of humanity, so it's important to know how these outbreaks spread,' said Javier Pizarro-Cerda, co-author of the study.
The researchers examined samples of Yersinia pestis, the bacteria that cause the plague, dating back to each pandemic.
In all three cases, the genes of each plague bacteria evolved to become less virulent and less deadly over time, according to the study.
By causing less severe infections, the bacteria are thought to have extended the length of the pandemics because it gained more opportunities to spread between people.
The researchers confirmed this theory by infecting rats with recent plague samples, showing that the disease lasted longer when the virulence decreased.
While antibiotics can now effectively fight off the plague, the research could shine a light on how other pandemics might evolve.
'This allows us to gain a comprehensive understanding of how pathogens can adapt to different situations,' Pizarro-Cerda said.
'We finally better understand what the plague is - and how we can develop measures to defend ourselves,' he added.
THE CAUSE BEHIND EUROPE'S BUBONIC PLAGUES
The plague, caused by the bacterium Yersinia pestis, was the cause of some of the world's deadliest pandemics, including the Justinian Plague, the Black Death, and the major epidemics that swept through China in the late 1800s.
The disease continues to affect populations around the world today.
The Black Death of 1348 famously killed half of the people in London within 18 months, with bodies piled five-deep in mass graves.
When the Great Plague of 1665 hit, a fifth of people in London died, with victims shut in their homes and a red cross painted on the door with the words 'Lord have mercy upon us'.
The pandemic spread from Europe through the 14th and 19th centuries - thought to come from fleas which fed on infected rats before biting humans and passing the bacteria to them.
But modern experts challenge the dominant view that rats caused the incurable disease.
Experts point out that rats were not that common in northern Europe, which was hit equally hard by plague as the rest of Europe, and that the plague spread faster than humans might have been exposed to their fleas.
Most people would have had their own fleas and lice, when the plague arrived in Europe in 1346, because they bathed much less often.