The Black Death, or bubonic plague, occurred between the years of 1347-1351. The rapid emergence of the disease caused by the pathogen Yersinia pestis (formerly Pasteurella pestis) is estimated to have claimed the lives of 30 to 50 percent of the European population at the time. In a paper published this month in the journal Nature, scientists discuss the reconstruction of the genome from samples of bacterial DNA recovered from the teeth of humans believed to have died from the plague.
The reason why genome sequencing of the pathogen is important is because descendants of Yersinia pestis still exist. Though yersinia infection can now be readily treated with antibiotics, it is believed that the particular strain responsible for the death of millions many years ago was much more virulent. Consequently, researchers are able to compare current strains with those of its ancestor to determine what in particular, if anything at all, was different and allowed it to cause so many deaths.
Indeed, as the authors of the study points out, the relative indolent nature of the current strain has questioned whether it was even yersinia that was responsible for the bubonic plague. However, in concluding the authors state:
"...we have reconstructed a draft genome for what is arguably the most devastating human pathogen in history, and revealed that the medieval plague of the fourteenth century was probably responsible for its introduction and widespread distribution in human populations."
The information that will be gained from evaluating the deadly disease and comparing it to more harmless strains that currently exist will give researchers the potential to learn about our past susceptibility to the pathogen and perhaps prevent any similar future strains' capacity to cause similar devastation.
- A draft genome of Yersinia pestis from victims of the Black Death (Nature, October 2011)