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Last updated at 16:21 BST, Thursday, 13 October 2011

Secrets of the plague


14 October 2011

The genetic code of the germ that caused the Black Death has been reconstructed by scientists for the first time.

The Black Death, also known as the plague, killed millions of people in Europe in the 14th Century.

Matt McGrath

Skeletons of plague victims

DNA samples were taken from skeletons found in London


Click to hear the report:


Humans have rarely encountered an enemy as devastating as the bacterium, Yersinia pestis. Between 1347 and 1351 it sparked the Black Death, an infection carried by fleas that spread rapidly across Europe killing around 50 million people.

Now scientists have uncovered some of the genetic secrets of the plague, thanks to DNA fragments drilled from the teeth of victims buried in a graveyard in East London.

The researchers say that all current strains circulating in the world are directly related to the medieval bacterium. And while the infection still kills 2,000 people globally every year, it's much less of a threat because our immune systems have adapted to it.

The scientists say the techniques used to rebuild the genome of the Black Death could now be used to reconstruct other ancient pathogens

Matt McGrath, BBC World Service


Click to hear the vocabulary:


rarely encountered

not often met or come into contact with


destructive and harmful


caused to start


tiny jumping insects which feed on the blood of animals and humans


small, incomplete pieces of


people who had died of the disease


versions of the disease

immune systems

our body's natural defence mechanism


changed and evolved to be able effectively to fight


small organisms that cause diseases