Scientists have sequenced the entire genome of the Black Death, the first time a team has managed to create a reconstructed genome of an ancient pathogen.

Between 1347 and 1351, the plague claimed the lives of 50 million Europeans, making it one of the worst epidemics in the history of mankind.

Published in the journal Nature, the new study allows the team to track changes to the virus over time and it is hoped this will lead to a better understanding of modern infectious diseases. The sequencing of the genome follows on from a separate study in which the team harvested tiny degraded DNA fragments of the causative agent of the Black Death, demonstrating the variant Yersinia pestis bacterium was responsible for the 50 million deaths.

Hendrik Poinar and Kirsten Bos of McMaster University and Johannes Krause and Verena Schuenemann of the University of Tubingen were the leaders of the study into the diseases, modern variants of which still kill 2,000 people each year.

"The genomic data show that this bacterial strain, or variant, is the ancestor of all modern plagues we have today worldwide. Every outbreak across the globe today stems from a descendant of the medieval plague.

"With a better understanding of the evolution of this deadly pathogen, we are entering a new era of research into infectious disease," Mr Poinar explained.

Now the team is looking to address what made the particular strain of the Black Death prevalent in the 1300s so deadly. Using the same methodology, the team should be able to sequence a number of other ancient pathogens.

The DNA sample was taken from the dental pulp of five bodies which had already been screened for the presence of Y. Pestis and were found in the so-call plague pits in London. The plague hit the UK in bubonic form in 1348, staying in the south of the country, before the pneumonic form spread across the entire UK by 1350.

Mr Poinar concluded: "We found that in 660 years of evolution as a human pathogen, there have been relatively few changes in the genome of the ancient organism, but those changes, however small, may or may not account for the noted increased virulence of the bug that ravaged Europe."