Black Death plague now blamed on giant gerbils, not rats

Rats, long believed to be the scourge that brought the Black Death to 14th-century Europe, may not be the disease-bearing scoundrels we thought they were.

Scientists have shifted blame for the medieval pandemic responsible for millions of deaths to a new furry menace: giant gerbils from Asia.

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"Climate-driven outbreaks of Yersinia pestis in Asian rodent plague reservoirs are significantly associated with new waves of plague arriving into Europe through its maritime trade network with Asia," write the authors of a report in Proceedings of the National Academy of Sciences.

The University of Oslo researchers, working with Swiss government scientists, say a "pulse" of strains arrived sporadically from Asia. They posit the Yersinia pestis bacterium was likely carried over the Silk Road via fleas on the giant gerbils during intermittent warm spells.

'Rewrite that part of history'

The fleas could have then transmitted the disease to humans.

Great gerbils, which are found in many parts of Central Asia, can grow to adult sizes of about 15-20 centimetres in body length.

The researchers say the findings offer "an alternative explanation" for how the pandemic, which peaked around 1347-1353, wiped out so many lives over the following four centuries.

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It was previously believed that black rats were the culprit, and that a single introduction of the pandemic in Europe was responsible. The Oslo and Swiss scientists now question the theory that a rat reservoir in Europe persisted during the time of Black Death.

If scientists with the University of California are correct, "we'll have to rewrite that part of history," University of Oslo biosciences Prof. Nils Christian Stenseth told BBC News.

The Black Death, also known as the bubonic plague, was one of the deadliest pandemics in history. It was believed to have killed up to 200 million people in Europe. Though very rare today, cases of the plague still arise in Africa, Asia, the Americas and parts of the former Soviet Union, with the World Health Organization reporting 783 cases worldwide in 2013, including 126 deaths.