Plague's origins ratted out: GERBILS not rats were the main cause of the Black Death

University of Oslo researchers say plague came from Asian great Gerbils; They say plague-carrying fleas flourished on the animals in warm weather; The fleas were then ferried to Europe via the Silk Road trading route; Black Death reduced the population in Britain by half when it struck

Rats have always been blamed for causing bubonic plague outbreaks in Europe, but now researchers claim they’ve been unfairly maligned and that it was actually gerbils that caused repeated epidemics of the disease.

The revelation comes from University of Oslo researchers who say they have compelling evidence that outbreaks of the plague, which killed millions in Europe after it arrived in the 14th century, can be traced back to great gerbils (Rhombomys opimus) from central Asia.

They say that the plague-carrying fleas flourished on the rodents before making their way to Europe via the Silk Road trading route.

Rat's amazing: University of Oslo researchers say they have compelling evidence that outbreaks of the plague can be traced back to great gerbils (pictured) from central Asia

Professor Stenseth and his team drew their conclusion after using tree-ring data to establish medieval weather patterns and compared these with thousands of Black Death records

They found that ideal weather patterns for the spread of the plague didn’t come from Europe, but Asia.

Fifteen years after a warm weather spell in Central Asia, a plague outbreak would occur in Europe. This pattern continued for hundreds of years.

Professor Stenseth said: ‘We show that wherever there were good conditions for gerbils and fleas in central Asia, some years later the bacteria shows up in harbour cities in Europe and then spreads across the continent.’

Gerbils numbers would increase, he said, whenever a hot summer followed a wet spring.

He added: ‘Such conditions are good for gerbils. It means a high gerbil population across huge areas and that is good for the plague. An increase in temperature of one degree will double the prevalence of plague in the gerbil population.’

Humans caught the plague from rats, but researchers say it was actually gerbils that were the original breeding ground for the disease

The fleas made their way to Europe in various stages. Some would have arrived via foxes that had eaten the gerbils, which then passed them onto rats, which passed them to humans.

In other cases humans may have caught the disease from camels, the fleas having jumped to them from the gerbils.

Filthy living conditions in 14th Britain have been blamed for allowing the Black Death to spread.

It remains one of the most destructive pandemics in history which peaked in Europe between 1348 and 1350.

Experts say it reduced the world's population from an estimated 450 million to almost 350 million in 1400.

In 1603 the killer plague returned and killed 38,000 Londoners.

The symptoms of the Black Death were revolting with historians noting descriptions of fever, muscle spasms, coughing up blood and black blood oozing out of swelling lymph nodes.

The most commonly noted symptom was the appearance of swollen lymph nodes on the groin, the neck and armpits, which often wept with pus and blood when they burst