New research employing cutting-edge DNA sequencing of exhumed soldiers has identified pathogens responsible for paratyphoid and relapsing fever, confirming that a cocktail of diseases, not just typhus, contributed to the immense mortality of Napoleon’s forces during their retreat from Russia in 1812.
The infamous 1812 Russian campaign, led by Napoleon Bonaparte, is etched into history as one of the most catastrophic military defeats. While historians have long attributed the demise of the Grande Armée to brutal winter conditions, starvation, and a rampant typhus epidemic, groundbreaking new research leveraging advanced ancient DNA analysis is rewriting this narrative. Scientists have now uncovered evidence of two previously unsuspected pathogens, significantly deepening our understanding of the complex factors that led to the army’s collapse.
The study, published in the journal Current Biology on October 24, 2025, reveals that paratyphoid fever and relapsing fever also plagued Napoleon’s soldiers. This discovery moves beyond the singular focus on typhus, suggesting a more insidious microbial onslaught that worked in concert with environmental hardships to decimate the invading forces.
Unearthing the Microbial Evidence
The journey to this discovery began with the excavation of a mass grave in Vilnius, Lithuania, in 2002. This site contained the remains of thousands of soldiers from Napoleon’s army, identified by artifacts like imperial guard buttons and belts. From these remains, scientists from the Institut Pasteur’s Microbial Paleogenomics Unit, in collaboration with the Laboratory of Biocultural Anthropology at Aix-Marseille University, meticulously extracted and analyzed the DNA of 13 soldiers.
Using cutting-edge next-generation sequencing techniques specifically adapted for ancient, degraded DNA, the research team searched for genetic signatures of infectious agents. Their innovative approach, developed with scientists from the University of Tartu in Estonia, included a phylogeny-driven interpretive method. This allowed them to accurately identify pathogens even from highly fragmented, low-coverage DNA, sometimes even pinpointing specific lineages. As study co-author and head of the Microbial Paleogenomics Unit at the Institut Pasteur, Nicolás Rascovan, explained, this method is crucial because “pathogen DNA is extremely fragmented and only present in very low quantities” in ancient human remains.
The Newly Identified Culprits: Paratyphoid and Relapsing Fever
The genetic analysis yielded significant findings:
- Salmonella enterica subsp. enterica (serovar paratyphi C), the bacterium responsible for paratyphoid fever, was detected in the teeth of four soldiers.
- Borrelia recurrentis, the pathogen causing relapsing fever (transmitted by lice), was found in two individuals.
These diseases, while distinct, share common and debilitating symptoms such as high fever, severe fatigue, and digestive problems. Their concurrent presence would have severely weakened soldiers already suffering from extreme cold, hunger, and dire sanitation conditions. Lead author Rémi Barbieri noted, “By just reading historical accounts, (it) was impossible to suspect these two pathogens.”
These findings complement earlier research that identified Rickettsia prowazekii (the typhus agent) and Bartonella quintana (the trench fever agent), both long believed to have ravaged the army. However, the new study’s samples did not detect typhus or trench fever, underscoring the idea that a broader spectrum of diseases was at play. As Rascovan emphasized, “What [the study] shows is that there was a whole range of diseases that were affecting these people.”
A Glimpse into the Past, Insights for the Future
While the study’s sample size (13 soldiers out of an estimated 300,000 who died during the retreat) limits the ability to determine the exact extent of these new pathogens’ contribution to the total mortality, it undeniably adds critical pieces to the historical puzzle. The correlation between the detected pathogens and symptoms described in historical accounts strengthens the theory that infectious diseases were a major, multi-faceted cause of the campaign’s collapse.
This research is more than just a historical revelation; it offers profound implications for our modern understanding of infectious diseases. “Accessing the genomic data of the pathogens that circulated in historical populations helps us to understand how infectious diseases evolved, spread and disappeared over time,” Rascovan stated. This information is invaluable for identifying the social and environmental contexts that influence disease dynamics, providing insights that can help us “better understand and tackle infectious diseases today.”
The ability to analyze ancient DNA with such precision represents a significant technological leap. As Cecil Lewis, an ancient DNA researcher at the Oklahoma School of Science and Mathematics, noted, we are now in an era where such studies can “contribute more nuance to the understanding of such historic events, which is exciting.” This ongoing evolution of scientific tools promises to unlock countless more secrets from our past, offering critical lessons for managing future health threats.
