An epidemic that erased a significant part of the population in Europe in the Middle and was the worst catastrophe in recorded history is again the talk of the town after hundreds of decade.

Also called ‘magna mortalitas’ (great mortality), emphasizing the death rate, the bubonic plague was the subject of study among many researchers and a recent study by scientists from the University of Oslo and the University of Ferrara has come out with a surprising find.

Humans - and not rats - could have been the cause of the spread of plague during the Black Death claimed the study.

It has long been thought that the plague, caused by the bacterium Yersinia pestis, which lasted in Europe until the early 19th century, was spread by rats.

But new studies reveal the epidemic that resulted in the deaths of an estimated 75 to 200 million people was caused actually by human "ectoparasites such as body lice and human fleas and not rats. The dirty living condition of humans aggravated the problem and made it spread all through Europe.

Using mortality data from nine plague outbreaks in Europe between the 14th and 19th centuries, the teams tracked how the plague developed.

They created models of how a disease could be spread by rats, airborne transmission, and fleas and lice on humans and clothes.

They found that, in seven of the cases, there was a close resemblance between the human model and the outbreak when compared with the other two alternatives.

When fleas infected with the bacterium Yersinia pestis bite humans, the bacteria can jump into the bloodstream and congregate in humans’ lymph nodes, which are found throughout the body

 People infected with plague usually develop "flu-like" symptoms after an incubation period of 3-7 days

Plague still is endemic in many countries. The three most endemic countries are Madagascar, the Democratic Republic of Congo and Peru