"The Epidemic That Brought Down Napoleon's Army Was Not What We Thought"

Institut Pasteur Analyzes Soldiers' DNA
Not Typhus, but Enteric Fever and Relapsing Fever Identified as the Cause

A new study has found that the epidemic which contributed to the downfall of Napoleon's army during the 1812 invasion of the Russian Empire was not typhus, as previously believed, but rather enteric fever and relapsing fever.

On October 25, the research team led by Dr. Nicolas Rascovan at Institut Pasteur in France announced that they had analyzed DNA extracted from the teeth of 13 Napoleon's soldiers excavated from a mass grave in Vilnius, Lithuania, in 2002. The analysis confirmed the presence of DNA from two pathogens that cause enteric fever and relapsing fever.

Napoleon army soldier's skull and soldier uniform buttons. Photo by Michel Signoli, Aix-Marseille University

In the summer of 1812, French Emperor Napoleon Bonaparte led a massive army of 500,000 to 600,000 troops to invade the Russian Empire. Although Napoleon's forces succeeded in occupying Moscow, they suffered devastating losses from starvation, cold, and epidemics during their retreat. By December of that year, only tens of thousands of soldiers survived. This campaign became a decisive turning point leading to the fall of the Napoleonic Empire.

The true nature of the epidemic that swept through Napoleon's army has been debated for centuries. At the time, physicians and officers argued based on records that the disease was typhus. This claim was supported by the discovery of body lice-known vectors of typhus-on the remains of Napoleon's soldiers, as well as the detection of typhus pathogen DNA.

However, the current research team approached the issue differently using state-of-the-art analysis methods.

Dr. Rascovan explained, "Ancient DNA is fragmented into very short pieces, making it difficult to analyze with PCR technology. However, in this study, we used advanced methods capable of capturing even these short fragments, allowing us to identify a broader range of pathogen DNA." Through this approach, the team detected the DNA of Salmonella enterica, which causes enteric fever, and Borrelia recurrentis, the pathogen responsible for relapsing fever and also transmitted by body lice, in the soldiers' teeth. In contrast, no traces or pathogens of typhus were found in the remains of the soldiers. Notably, the researchers also discovered that the Borrelia recurrentis strain identified in the soldiers belonged to the same lineage as a strain that existed in Iron Age Britain about 2,000 years ago.

Dr. Rascovan stated, "Ancient DNA analysis technology is a powerful tool for uncovering the evolution of infectious diseases. It's fascinating that we can now use modern techniques to identify and diagnose the cause of the epidemic that plagued Napoleon's army after 200 years."

The findings of this study were published in the scientific journal Current Biology.

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