Lice, Ancient DNA, and Napoleon’s Grand Army

Identification of human body lice. (Raoult et al, 2006)
Identification of human body lice. (Raoult et al, 2006)

Life in Napoleon’s Grand Army wasn’t always so grand. The Russian campaign was a disaster, recently most tangibly manifest in the mass grave found at Vilnius, Lithuania, in 2001. Local records suggested that the remains belonged to Napoleon’s soldiers who paused at Vilnius during their retreat from Moscow in 1812. The densely packed bodies were buried at the same time leaving behind buttons, buckles and gear of 40 regiments of Napoleon’s army. The initial trench revealed 717 skeletons at 7 corpses per meter squared, predicting 2000-3000 corpses at the site. Winter weather may have claimed most of the soldiers, but they were also known to have been plagued by lice and fevers.

For Raoult et al (2006) this was the perfect test case for detecting lice and louse-borne diseases in archaeological remains. After perfecting their technique of isolating cultured, dried human lice (Pediculus humanus humanus) in the laboratory*, they obtained soil from the mass grave at Vilnius. They isolated fragments of five lice from two kilograms of soil containing remains of bones and clothing, and confirmed the identification by “binocular magnification” (right), scanning electron microscopy and isolated P. humanus humanus DNA to confirm the species. Three of the lice produced Bartonella quintana DNA (trench fever) but none of the lice yielded Rickettsia powazekii DNA (typhus) or Borellia recurrentis DNA (relapsing fever).

They extracted DNA from 72 unerupted teeth from 35 skeletons for ‘suicide’ PCR pathogen detection. They found R. powazekii (typhus) in teeth from three skeletons and B. quintana (trench fever) teeth from seven skeletons. Overall, louse-transmitted disease was identified in 10 out of 35 skeletons (28.6%). B. quintana is believed to be the most common louse-transmitted pathogen in Antiquity and the Middle Ages. Trench fever alone is usually not fatal but when combined with the harsh conditions on the retreat from Russia it could have been a significant contributing factor. Epidemic typhus on the other hand is a more virulent organism and is more likely to be the cause of death of the three individuals in whose teeth R. powazekii was discovered.

The ability to identify pathogen vectors, in this case the human louse, and amplify pathogen DNA from both ancient vectors and humans is a big advance in our understanding of infectious disease in pre-modern populations.

* I don’t envy the research assistants or students who had to maintain the colonies of human lice in the lab, or roast them incubators to simulate conditions in soil.
Raoult D, Dutour O, Houhamdi L, Jankauskas R, Fournier PE, Ardagna Y, Drancourt M, Signoli M, La VD, Macia Y, & Aboudharam G (2006). Evidence for louse-transmitted diseases in soldiers of Napoleon’s Grand Army in Vilnius. The Journal of infectious diseases, 193 (1), 112-20 PMID: 16323139

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