Study suggests two unsuspected pathogens struck Napoleon's army during the retreat from Russia in 1812
Painting of Napoleon's army.
Credit
Barbieri et al., Current Biology
Institut Pasteur
image:
Imperial Guard button discovered during excavation. © UMR 6578 Aix-Marseille Université, CNRS, EFS
view moreCredit: © UMR 6578 Aix-Marseille Université, CNRS, EFS
Scientists from the Institut Pasteur have genetically analyzed the remains of former soldiers who retreated from Russia in 1812. They detected two pathogens, those responsible for paratyphoid fever and relapsing fever, which correlate with the symptoms described in historical accounts. The study was published as a preprint on bioRxiv on July 16, 2025. It will be published in the journal Current Biology on October 24.
The famous Russian campaign led by Napoleon in 1812, also known as the "Patriotic War of 1812," ended with the retreat of the French army. Scientists from the Institut Pasteur's Microbial Paleogenomics Unit, in collaboration with the Laboratory of Biocultural Anthropology at Aix Marseille University*, set out to investigate which pathogens may have caused major infectious disease outbreaks that contributed to this historical episode. They extracted and analyzed the DNA of 13 soldiers from Napoleon's army exhumed in Vilnius, Lithuania in 2002 during excavations led by the Aix-Marseille University team specialized in archeo-anthropology. The scientists then used next-generation sequencing techniques applied to ancient DNA to identify potential infectious agents.
Their research identified the genetic signatures of two infectious agents: Salmonella enterica subsp. enterica (serovar Paratyphi C), responsible for paratyphoid fever, and Borrelia recurrentis, responsible for relapsing fever, a disease transmitted by lice and characterized by bouts of fever followed by periods of remission. Although these two diseases are different, they can result in similar symptoms such as high fever, fatigue and digestive problems, and their simultaneous presence may have contributed to the soldiers' worsening state, especially as they were already weakened by cold, hunger and a lack of sanitation.
Of the 13 Napoleonic soldiers exhumed in Vilnius, the teeth of four tested positive for S. enterica Paratyphi C and two for B. recurrentis. This study provides the first genetic evidence of these two largely unsuspected infectious agents, although their precise role in the high number of deaths in the Grande Armée during its retreat from Russia is not known. Confirmation of the presence of these two bacteria comes after a previous study identified the typhus agent, Rickettsia prowazekii, and the trench fever agent, Bartonella quintana, pathogens long believed to be associated with the retreat based on historical accounts.
Given the low number of samples analyzed in comparison with the thousands of bodies found, it is impossible to determine the extent to which these pathogens contributed to the extremely high mortality observed. The scientists' analysis was based on a limited number of samples (13 out of more than 3,000 bodies in Vilnius and some 500,000 to 600,000 soldiers in the military force, around 300,000 of whom died during the retreat).
"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, and to identify the social or environmental contexts that played a part in these developments. This information provides us with valuable insights to better understand and tackle infectious diseases today," explains Nicolás Rascovan, Head of the Microbial Paleogenomics Unit at the Institut Pasteur and last author of the study.
To achieve these results, the team worked in collaboration with scientists from the University of Tartu in Estonia to develop an innovative authentication workflow involving several steps, including a phylogeny-driven interpretive approach for the highly degraded genome fragments recovered. This method enables scientists to accurately identify pathogens even if their DNA only yields low coverage, in some cases even indicating a specific lineage.
"In most ancient human remains, pathogen DNA is extremely fragmented and only present in very low quantities, which makes it very difficult to obtain whole genomes. So we need methods capable of unambiguously identifying infectious agents from these weak signals, and sometimes even pinpointing lineages, to explore the pathogenic diversity of the past," he adds.
This new study reveals a correlation between historical descriptions of the diseases suffered by Napoleon's army and the typical symptoms of paratyphoid and relapsing fever. It offers new evidence to support the theory that infectious diseases were one cause of the collapse of the 1812 campaign, alongside multiple other factors such as exhaustion, extreme cold and harsh conditions.
The Russian campaign led by Napoleon in 1812 ultimately ended in military defeat, resulting in a devastating retreat of the French army. This enabled the Russian army to regain control of Moscow and dealt a huge blow to the Emperor's strategy.
* Aix Marseille Univ, CNRS, EFSD, ADES, Marseille, France
Source
Paratyphoid fever and relapsing fever in 1812 Napoleon’s devastated army, Current Biology, 24 octobre 2025
Rémi Barbieri,1 Julien Fumey,1,2 Helja Kabral,3 Christiana Lyn Scheib,3,4 Michel Signoli,5 Caroline Costedoat,5 and Nicolas Rascovan1,6,*
1Institut Pasteur, Université de Paris Cité, CNRS UMR 2000, Microbial Paleogenomics Unit, 75015 Paris, France
2Institut Pasteur, Université Paris Cité , Bioinformatics and Biostatistics Hub, 75015 Paris, France
3Estonian Biocentre, Institute of Genomics, University of Tartu, 51010 Tartu, Estonia 4Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
5Aix Marseille Université, CNRS, EFS, ADES, Pierre Dramard Boulevard, 13015 Marseille, France
6Lead contact
https://doi.org/10.1016/j.cub.2025.09.047
Journal
Current Biology
Method of Research
Experimental study
Subject of Research
Human tissue samples
Article Title
Paratyphoid fever and relapsing fever in 1812 Napoleon’s devastated army, Current Biology
Article Publication Date
24-Oct-2025
DNA from Napoleon’s 1812 army identifies the pathogens likely responsible for the army’s demise during their retreat from Russia
Cell Press
image:
Skull of a soldier from the Napoleon army next to a button from a soldier's uniform.
view moreCredit: Michel Signoli, Aix-Marseille Université
In the summer of 1812, French emperor Napoleon Bonaparte led about half a million soldiers to invade the Russian Empire. But by December, only a fraction of the army remained alive. Historical records suggest that starvation, cold, and typhus led to their demise. In a new study publishing October 24 in the Cell Press journal Current Biology, a team of microbial paleogenomicists extracted DNA from the soldiers’ teeth and found no trace of typhus. Instead, they identified two pathogens known to cause enteric fever and relapsing fever—ailments which likely contributed to the army’s downfall.
“It’s very exciting to use a technology we have today to detect and diagnose something that was buried for 200 years,” says lead author Nicolás Rascovan of the Institut Pasteur in France.
For centuries, historians have debated the factors that contributed to Napoleon’s army’s demise. Accounts from doctors and army officers suggested it was likely the result of typhus, an infectious disease that was common among armies of the time. The discovery of body lice—the main vector of typhus—on the remains of Napoleon’s soldiers, and the DNA of Rickettsia prowazekii—the bacterium responsible for typhus—further bolstered this assumption.
With new technology in hand capable of analyzing ancient DNA, Rascovan and his team set off to reanalyze samples from Napoleon’s fallen soldiers to see whether typhoid was indeed the culprit.
The researchers extracted and sequenced DNA from the teeth of 13 soldiers buried in a mass grave in Vilnius, Lithuania, which was along the route of the French army’s retreat from Russia. They then removed all environmental contamination to isolate and identify DNA fragments from bacterial pathogens.
Instead of pathogens for typhus, the team found traces of Salmonella enterica, a bacterium that causes enteric fever, and Borrelia recurrentis, responsible for relapsing fever, which is also transmitted by body lice.
The researchers did not detect R. prowazekii or Bartonella quintana, the cause of trench fever, which has been identified in previous research on different soldiers from this site. Rascovan says this discrepancy could be explained by the usage of different sequencing technologies. Earlier studies relied on polymerase chain reaction, or PCR, a technology that makes many copies of a specific DNA segment from limited starting material.
“Ancient DNA gets highly degraded into pieces that are too small for PCR to work. Our method is able to cast a wider net and capture a greater range of DNA sources based on these very short ancient sequences,” says Rascovan.
To the team’s surprise, they also found that the B. recurrentis strain found on Napoleon’s soldiers belonged to the same lineage that was recently found to be present in ancient Britain 2,000 years earlier during the Iron Age. This lineage somehow persisted for millennia in Europe, but all present-day strains sequenced so far belong to a different lineage.
“This shows the power of ancient DNA technology to uncover the history of infectious diseases that we wouldn't be able to reconstruct with modern samples,” Rascovan says.
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This work was supported by the European Research Council, the Institut Pasteur, the French National Centre for Scientific Research, and the French National Research Agency.
Current Biology, Barbieri et al., “Paratyphoid fever and relapsing fever in 1812 Napoleon's devastated army” https://www.cell.com/current-biology/fulltext/S0960-9822(25)01247-3
Current Biology (@CurrentBiology), published by Cell Press, is a bimonthly journal that features papers across all areas of biology. Current Biology strives to foster communication across fields of biology, both by publishing important findings of general interest and through highly accessible front matter for non-specialists. Visit: http://www.cell.com/current-biology. To receive Cell Press media alerts, contact press@cell.com.
Journal
Current Biology
Method of Research
Experimental study
Subject of Research
People
Article Title
Paratyphoid Fever and Relapsing Fever in 1812 Napoleon's Devastated Army
Article Publication Date
24-Oct-2025
1812 OVETURE WITH CANNONS
