Ancient DNA Reveals Hidden Pathogens Behind Napoleon’s Russian Campaign
A groundbreaking new study has identified paratyphoid fever and relapsing fever as likely contributors to the devastating losses suffered by Napoleon’s army during its 1812 retreat from Russia, offering the first genetic evidence of these diseases in the soldiers. The
The study, published in the journal PLOS Pathogens on October 24.
The ill-fated Russian campaign, also known as the “Patriotic War of 1812,” culminated in a disastrous retreat for the French forces. Scientists at the Institut Pasteur, in collaboration with Aix Marseille University, embarked on a mission to pinpoint the infectious agents responsible for the widespread disease outbreaks that plagued the Grande Armée.Their examination involved analyzing the remains of 13 soldiers exhumed from a mass grave in Vilnius,Lithuania,in 2002.
Using advanced next-generation sequencing techniques on ancient DNA, the team successfully identified the genetic signatures of two key pathogens: Salmonella enterica subsp. enterica (serovar Paratyphi C), the cause of paratyphoid fever, and Borrelia recurrentis, responsible for relapsing fever. this latter disease is transmitted by lice and characterized by recurring bouts of fever interspersed with periods of remission.
While distinct illnesses, both paratyphoid and relapsing fever share overlapping symptoms – including high fever, fatigue, and digestive issues – which likely compounded the soldiers’ suffering.This was particularly true given their already weakened state due to exposure to extreme cold, starvation, and unsanitary conditions.
Analysis of the remains revealed that four of the 13 soldiers tested positive for S. enterica Paratyphi C, while two carried B. recurrentis. This study builds upon previous research that identified rickettsia prowazekii (typhus) and Bartonella quintana (trench fever) as also present during the retreat, confirming long-held past suspicions.
However, researchers caution against drawing definitive conclusions about the overall impact of these pathogens.”Given the limited number of samples analyzed – 13 out of over 3,000 bodies discovered in vilnius, and a tiny fraction of the 500,000 to 600,000 soldiers who comprised the force – it’s unfeasible to determine the extent to which these pathogens contributed to the extremely high mortality observed,” a senior official stated. approximately 300,000 soldiers perished 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,” explained Nicolás Rascovan, Head of the Microbial Paleogenomics Unit at the Institut Pasteur and the study’s lead author. “This details provides us with valuable insights to better understand and tackle infectious diseases today.”
The team overcame significant technical hurdles to achieve these results,collaborating with scientists at the University of Tartu in Estonia to develop a novel authentication workflow. This involved a “phylogeny-driven interpretive approach” to accurately identify pathogens from highly fragmented DNA. “In most ancient human remains, pathogen DNA is extremely fragmented and only present in very low quantities, which makes it very arduous to obtain whole genomes,” one researcher noted. “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.”
This new evidence strengthens the theory that infectious diseases played a significant role in the collapse of Napoleon’s 1812 campaign, alongside well-documented factors like exhaustion, brutal weather, and logistical failures. The study reveals a compelling correlation between historical accounts of the soldiers’ illnesses and the known symptoms of paratyphoid and relapsing fever.
Ultimately, the Russian campaign ended in a decisive military defeat for Napoleon, forcing a harrowing retreat that crippled his army and dealt a severe blow to his imperial ambitions. The findings underscore the often-overlooked role of microscopic adversaries in shaping the course of history.
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