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Paris, May 31, 2025 — In a groundbreaking study published in the journal Science, researchers have revealed that the bacteria responsible for the plague, Yersinia pestis, evolved over centuries to become less deadly. This adaptation, scientists say, allowed the bacteria to persist and spread across three major pandemics, shaping the course of human history.
Evolution of a Historic Killer
The plague, infamous for its catastrophic impact during the Middle Ages, struck in three major waves:
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The Plague of Justinian (500s–700s): The first recorded pandemic, lasting nearly 200 years.
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The Black Death (mid-1300s): The deadliest pandemic in history, wiping out up to half the population in Europe, western Asia, and Africa, with outbreaks recurring for centuries.
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The Third Pandemic (1850s–present): Originating in China, this wave continues today, with sporadic cases still reported in parts of sub-Saharan Africa.
Bacteria Became Less Lethal to Survive
Researchers, led by Javier Pizarro-Cerda of France’s Pasteur Institute, analyzed samples of Yersinia pestis from each pandemic. Their findings show that, over time, the bacteria’s genes evolved to reduce their virulence. By causing less severe infections, the plague bacteria were able to infect more people for longer periods, increasing their chances of survival and transmission.
To test this theory, the team infected rats with modern samples of the bacteria. Results confirmed that less virulent strains led to longer-lasting infections, supporting the idea that decreased lethality can prolong a pathogen’s presence in the population.
Implications for Modern Pandemics
While antibiotics today can effectively treat the plague, this research offers valuable insights into how pathogens adapt and persist. “This allows us to gain a comprehensive understanding of how pathogens can adapt to different situations,” said Pizarro-Cerda. “We finally better understand what the plague is — and how we can develop measures to defend ourselves.”
The study’s findings could also inform strategies for managing future pandemics, as understanding pathogen evolution is key to developing effective public health responses.
Disclaimer:
This article is based on findings published in the journal Science and reported by the Economic Times Health. The information provided is for educational and informational purposes only and should not be considered as medical advice. For health-related concerns or questions about infectious diseases, please consult a qualified healthcare professional.
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