Medieval Plagues and the Role of Lice

We’ve all heard about the biblical plague of the mid-fourteenth century thatwiped out more than half of Europe by killing  75 to 200 million people. History tells us that the pandemic originated in Central Asia and was brought to Europe by rodents on trade ships. However, research conducted by a team from the University of Oslo found evidence that suggests that it was lice and fleas which were responsible for killing millions of people, ultimately causing the infamous Black Death. So did rats get a bad rap for no reason? Let’s take a look at what research has found!

What did the research say?

In recent years, several doubts about the rat theory developed. The hypothesis was that rats wouldn’t have been able to spread the plague as fast as history suggests. This prompted a team of researchers to gather mortality records from Europe during the 14th to 19th centuries. They created a mathematical model to demonstrate several possibilities regarding the outbreak of the black plague. Three different scenarios were created for the model—either the diseases were spread by airborne transmission, rats, or lice. An assessment of the scenarios led to the conclusion that an outbreak caused by lice is the best match to what went down in history. The other scenarios presented minimal evidence. The study also showed that lice were common in people during the fourteenth century due to lack of sanitation and bathing.

The deadly lice bite

The paper was published in Proceedings of the National Academy of Sciences. It asserted that lice and flees infected with bacteria called Yersinia pestis bit human beings. The bacteria entered the bloodstream and caused the lymph nodes on the human body to swell and become bulbous. While it may be true that rats brought the disease to Europe, they weren’t responsible for spreading it. The Yersinia pestis may have infected the rats but lice and fleas drank their blood and transmitted the disease onto humans.

Other research

To assess the validity of the claims made in the paper, several studies were conducted to replicate the results. Scientists at the Argonne National Laboratory statistically evaluated the same models to match the mortality patterns in nine different cities and found that the human-lice model fit mortality records. It turns out that rats might not be to blame for the Black Death, after all! If you’re looking for lice removal services in New York, head over to Lice Troopers’ lice removal salon for their pesticide free and effective treatments to get rid of lice. Contact us at 800-403-5423 for more information.