In less than six months, over a half a million of Napoleon’s soldiers had succumbed to starvation, hypothermia, and disease. The discovery of typhus’ main vector–body lice–on bodily remains coupled with trace DNA of typhus’ bacterial cause (Rickettsia prowazekii) further supported this narrative. The former bacterium is responsible for enteric or typhoid fever, while the latter causes relapsing fever. Meanwhile, relapsing fever is often transmitted by body lice. “Ancient DNA gets highly degraded into pieces that are too small for PCR to work,” Rascovan said in a statement.