30 Aug 2011

Using DNA to trace the cause of the Black Death

Scientists have extracted DNA from the skeletons of plague victims found at a mass grave in London in their quest to find what caused the Black Death.

The latest study, by a team from universities in Canada and Germany, looked for surviving fragments of DNA in bones and teeth.

“Without a doubt, the plague pathogen known today as ‘yersinia pestis’ was also the cause of the plague in the middle ages,” said Johannes Krause of Tubingen University.

The research reveals yersinia pestis shares part of the same gene sequence as the modern bubonic plague. It is still present in countries such as India, although an outbreak in Bombay in 1904 only killed only 3 per cent of its victims.

By contrast, the Black Death, which swept through Europe between 1348 to 1353, is thought to have killed one-third of London’s citizens.

The study’s authors hope that even though the disease that caused the Black Death is probably extinct, further study could reveal how it evolved into a less virulent strain.

2,400 victims were buried at a special cemetery a few metres from the Tower of London, which provided the DNA for the study.

“Having the results that they’ve got from this analysis will hopefully provide a greater insight into what it actually was, how it was transmitted, and the type that it is,” Jelena Bekvalac, the Museum of London’s curator of human osteology, told Channel 4 News.

The research also indicates that the yersina pestis microbe was not present on the British mainland prior the Black Death, which suggests it reached this country from elsewhere.