The Evolution of Plague Bacteria: How Adaptation Led to Longer Pandemics
A recent study has shed light on the fascinating evolution of the bacteria responsible for causing the plague, showcasing how these pathogens adapted over time to become less deadly, ultimately prolonging their ability to infect humans across three major pandemics spanning over a thousand years.
The first pandemic, known as the plague of Justinian, emerged in the 500s during the early Middle Ages and persisted for approximately two centuries. This was followed by the infamous Black Death in the mid-1300s, which ravaged Europe, western Asia, and Africa, claiming the lives of up to half of the population in these regions. The third bubonic plague pandemic erupted in China in the 1850s and continues to pose a threat today, with sporadic cases still reported in parts of Africa.
Microbiologist Javier Pizarro-Cerda from France’s Pasteur Institute, a co-author of the study published in the journal Science, emphasized the significance of understanding the spread of these outbreaks. He highlighted how the plague bacteria played a pivotal role in shaping human history.
The research involved analyzing samples of Yersinia pestis, the bacteria responsible for causing the plague, from each of the three pandemics. Surprisingly, the study revealed that over time, the genes of the plague bacteria evolved to become less virulent and lethal, a pattern observed in all three instances.
By causing milder infections, the plague bacteria were able to prolong the duration of the pandemics as they had more opportunities to spread among individuals. This hypothesis was confirmed through experiments involving the infection of rats with recent plague samples, demonstrating that the disease persisted longer when the virulence of the bacteria decreased.
While modern antibiotics are now effective in combating the plague, this research provides valuable insights into how pathogens can adapt and evolve in different environments. Pizarro-Cerda emphasized the importance of this knowledge in understanding and potentially combating future pandemics.
“This research not only enhances our understanding of the plague but also offers valuable insights into how we can develop strategies to protect ourselves from similar infectious diseases,” Pizarro-Cerda concluded.
© Agence France-Presse
