Plague germs teased from medieval cadavers in a London cemetery have shed light on why the bacterium that unleashed the Black Death was so lethal and spawned later waves of epidemics.
Plague germs teased from mediaeval cadavers in a London cemetery have shed light on why the bacterium that unleashed the Black Death was so lethal and spawned later waves of epidemics.
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The DNA of Yersinia pestis shows, in evolutionary terms, a highly successful germ to which the population of 14th-century Europe had no immune defences, according to a study published Wednesday in the British journal Nature.
It also lays bare a pathogen that has undergone no major genetic change over six centuries.
"The Black Death was the first plague pandemic in human history," said Johannes Krause, lead researcher and a professor at the University of Tuebingen, Germany.
"Humans were (immunologically) naive and not adapted to this disease," he said in an email exchange.
No bug or virus has wiped out a greater proportion of humankind in a single epidemic than the Black Death.
Brought to Europe from China, it scythed through the continent from 1347 to 1351, killing about 30 million people -- about one in three of Europe's and nearly one in 12 of the world's population at the time.
Remarkably, more recent variants of the bacterium hardly vary compared to the original microbe, says the paper.
"Based on the reconstructed genome, we can say that the mediaeval plague is close to the root of all modern human pathogenic plague strains," said Krause.
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