15:56 28 January 2014
Researchers who studied the Plague of Justinian, a massive outbreak that killed half of the world’s population in the 6th century, have found it was caused by a different strain to the Black Death in the 14th Century.
The Justinian was an evolutionary 'dead end', arriving to do its damage and then leaving well before the Black Death which was something else entirely.
After isolating genetic traces of plague from the teeth of 1,500-year-old victims, the researchers warned that the Black Death could strike again. They added that the new strain can reappear without warning.
Northern Arizona University's Dr Dave Wagner said: "We know the bacterium Y pestis has jumped from rodents into humans throughout history and rodent reservoirs of plague still exist today in many parts of the world.
"If the Justinian plague could erupt in the human population, cause a massive pandemic, and then die out, it suggests it could happen again.
"Fortunately we now have antibiotics that could be used to effectively treat plague, which lessens the chances of another large-scale human pandemic."
The Plague of Justinian is widely blamed for the death of 30 million to 50 million people throughout Asia, North Africa, the Middle East, and Europe. 800 years later, the Black Death killed 50 million Europeans between 1347 and 1351.