Napoleon's doomed retreat: DNA from Vilnius mass grave reveals signs of foodborne and lice-borne fever

Justin Jackson
褋ontributing writer

Sadie Harley
scientific editor

Robert Egan
associate editor

Institut Pasteur and partner institutions report genetic evidence of Salmonella enterica lineage Para C and Borrelia recurrentis in Napoleonic soldiers from Vilnius, indicating paratyphoid fever and louse-borne relapsing fever were present during the 1812 retreat.
Napoleon assembled about 500,000鈥600,000 soldiers to invade Russia in 1812. After arriving in Moscow without decisively defeating the Russian army, the Napoleonic forces found themselves isolated in a ruined city and initiated a retreat to establish winter encampments along the border with Poland.
Retreat from Russia spanned October 19 to December 14, 1812 and resulted in massive losses attributed by historians to cold, hunger, and diseases. 糖心视频icians and officers documented typhus, diarrhea, dysentery, fevers, pneumonia, and jaundice.
Previous reports described body lice in Vilnius remains and PCR-based claims of Rickettsia prowazekii and Bartonella quintana using short fragments, alongside Anelloviridae in other soldiers from Kaliningrad.
In the study, "Paratyphoid Fever and Relapsing Fever in 1812 Napoleon's Devastated Army," on the pre-print server bioRxiv, researchers recovered and sequenced ancient DNA from the teeth of soldiers who likely died from infectious diseases to identify pathogens that could have contributed to their deaths.
The sampling drew on 13 intact teeth from different individuals recovered from a mass grave in Vilnius, Lithuania associated with the December 1812 retreat, from a site with a minimum of 3,269 exhumed individuals. No battle trauma was observed at the site.
Initial analysis flagged fourteen possible pathogens. Salmonella enterica and Borrelia recurrentis showed the strongest signals. Four soldiers (87A, 92B, 95A and 97B) yielded between roughly 30 and 970 unique DNA fragments matching the Paratyphi C strain, with read-mismatch patterns indicating authentic ancient bacterial DNA.
Sample 93A produced about 4,060 unique fragments covering the chromosome and all seven plasmids of B. recurrentis, while 92B contributed around 320 unique reads and 18 confirmed hits after detailed filtering.
Phylogenetic placement positioned all Salmonella sequences firmly within the Paratyphi C lineage, a pathogen known to cause paratyphoid fever. No authenticated DNA matches Rickettsia prowazekii or Bartonella quintana. While no authenticated reads for R. prowazekii or B. quintana were found, the authors note this does not rule out their presence due to limitations of ancient DNA preservation.
Authors conclude that paratyphoid fever lineage Para C and louse-borne relapsing fever were present among Napoleonic soldiers during the 1812 retreat.
Historical testimony described widespread diarrhea and consumption of salted beets and brine along the route to Vilnius, consistent with a foodborne route for paratyphoid fever.
A scenario of fatigue, cold, and overlapping infections likely contributed to mortality. Analysis of a larger number of samples is recommended to define the full spectrum of epidemic diseases at the site, and a phylogeny-driven authentication workflow is presented for ultra-low-coverage pathogen ancient DNA.
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More information: R茅mi Barbieri et al, Paratyphoid Fever and Relapsing Fever in 1812 Napoleon's Devastated Army, bioRxiv (2025).
Journal information: bioRxiv
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