Plague Returned to Europe for 400 Years After the Black Death
Ancient DNA shows the disease spread via trade and war, creating new reservoirs in wild rodent populations across Europe.
Key points
- Plague returned to Europe for over 400 years after the Black Death, spreading via trade and war.
- Researchers reconstructed 26 plague genomes from human remains in five European countries.
- A new dating method links ancient plague genomes to specific historical outbreaks.
The Black Death is widely remembered as a single catastrophic wave that killed millions between 1347 and 1353. However, new research indicates that the plague did not disappear after this initial disaster. Instead, the disease continued to return to Europe for more than four centuries, repeatedly disrupting cities, economies, and societies long after the 14th century.
A study led by the University of Tartu provides a detailed reconstruction of this long period. By analyzing the DNA of the plague bacterium, Yersinia pestis, preserved in human remains, scientists have traced how the disease evolved and spread. The findings suggest that plague was not a static threat from a single source, but a dynamic pathogen that adapted and reappeared through trade, migration, and war.
Genomes reveal multiple plague origins
Researchers reconstructed 26 distinct genomes of the plague bacterium from archaeological sites in Estonia, Russia, England, the Netherlands, and Switzerland. These samples span the 14th to 18th centuries, covering the majority of the Second Plague Pandemic. The genetic evidence contradicts the idea that the disease simply survived in one location and spread outward. Instead, it points to repeated introductions of the bacterium into different regions of Europe.
Estonia was particularly affected, with signs of plague entering the region multiple times during this period. This pattern highlights how interconnected European populations were, allowing the disease to move across long distances. The study identifies several previously unknown genetic lineages in both urban and rural settings, indicating that the bacterium established itself in various local populations rather than remaining confined to major ports or cities.
Climate change aided rodent population shifts
One significant pattern emerged between 1450 and 1500, when plague lineages expanded and split into three major branches. These branches likely helped establish new reservoirs of Yersinia pestis in wild rodent populations. The researchers suggest that climate factors, specifically the Great Renaissance Drought, may have played a role. Modern studies show that climate changes can strongly affect outbreaks among wild rodents, which serve as natural hosts for the bacterium.
New method dates ancient infections
A major challenge in studying historical pandemics is determining exactly when ancient infections occurred. Unlike modern viruses, which can be tracked with precise dates, archaeological remains often rely on radiocarbon dating that provides wide time windows, sometimes spanning over a century. This lack of precision limits the ability to interpret genetic data and link specific strains to recorded historical outbreaks.
To address this, the team developed a method to narrow these broad dating ranges. By examining specific genetic markers and comparing them with historical records, they were able to link many ancient genomes to specific outbreaks. This approach allows for a more accurate timeline of plague transmission, bridging the gap between genetic evidence and historical documentation. The work, reported by ScienceDaily and others, offers a clearer picture of how the second plague pandemic persisted and evolved over centuries.
