DNA tests conducted in Germany found that the bacteria that causes bubonic plague caused London’s Great Plague of 1665-1666.
The Max Planck Institute for the Science of Human History tested teeth from recovered dead bodies and found positive results of yersinia pestis in five out of 20 skeleton samples, the BBC reports. This bacteria was also responsible for the 14th century Black Death. The Great Plague skeletons were exhumed from a mass grave at Liverpool Street in London, where a new railway is being built, according to the Museum of London Archaeology.
The remains don’t pose a risk today, because the bacteria cannot survive time in the ground and died shortly after its host. The plague, the last major outbreak in Britain, killed nearly a quarter of the population.
Scientists from Max Planck and the Museum of London Archaeology say the next step is to compare this DNA with DNA recovered from a 14th-century plague to see where the disease originally came from, National Geographic reports.
“We want to know if there was a local/European plague focus—a reservoir of the disease within a rodent population—or were there separate waves of plague coming from Asia,” MOLA’s Don Walker told National Geographic. “Current evidence suggests the former.”