Infectious Disease For 400 Years After the Black Death, Plague Kept Walking Back Into Europe on War Roads
Twenty-six sets of medieval teeth trace Yersinia pestis splitting into three branches around 1500, with the later lineages tracking the roads armies and refugees traveled. The pattern points to repeated re-introductions, plus some strains that may have dug in locally.
By Sarah Okonkwo · September 21, 2026