JENA, Germany, Jan. 25 (UPI) -- The plague known as the Black Death is estimated to have killed roughly half of Europe's population during the 14th century. The pathogens did most of their damage between 1346 and 1353, but new research shows the plague persisted through the 18th century.
Although scientists have made great strides in retracing the path of the Black Death, questions remain about its genesis and evolution.
Recently, researchers at the Max Planck Institute for the Science of Human History were able to reconstruct the pathogen genomes via analysis of DNA samples collected from the victims of the Great Plague of Marseille.
The Black Death's reemergence in the southeastern French port city between 1720 and 1722 is considered the last outbreak of medieval plague in Europe.
"We faced a significant challenge in reconstructing these ancient genomes," computational analyst Alexander Herbig said in a press release. "To our surprise, the 18th century plague seems to be a form that is no longer circulating, and it descends directly from the disease that entered Europe during the Black Death, several centuries earlier."
The results of their genetic analysis are detailed in a new paper, published in the journal eLife.
The genomes Herbig and his colleagues identified are different than the types of plague found today, which suggests the strain that afflicted Marseille is now extinct, but was quite similar to the strains that first emerged in the 14th century.
Because Marseille is a historic port city -- an epicenter of world trade since its ancient Greek beginnings -- determining exactly where the pathogens came from is quite difficult.
But researchers believe the plague was hanging out in Europe in between its medieval outbreaks.
"Our results suggest that the disease was hiding somewhere in Europe for several hundred years," said Kirsten Bos, the study's lead author.
Further study of the genomes may help scientists understand how the pathogens went into a sort of hibernation, and what made them periodically reemerge. They may also be able to learn why the plague of medieval times is largely absent from the modern world.
"It's a chilling thought that plague might have once been hiding right around the corner throughout Europe, living in a host which is not known to us yet," added researcher Johannes Krause. "Future work might help us to identify the mysterious host species, its range and the reason for its disappearance."