NBC News Lab experiments support the possibility that the blood-sucking bugs may have played a role in the rapid spread of the plague in the Middle Ages.
Scientists have long debated whether human body lice might have helped drive the rapid spread of the bacteria responsible for the deadly plague in the Middle Ages, known as the Black Death.
It’s clear that rat fleas played a major role, but some population studies have suggested that bites from those fleas might not have been enough to drive a plague that killed tens of millions in Europe, Asia and other countries in the 14th century.
A study published Tuesday in PLOS Biology suggests that body lice may be more efficient at transmitting the plague bacteria, Yersinia pestis, than previously thought and thus might have helped drive up the numbers in the bubonic plague pandemic.
Body lice are parasites that can spread disease and usually affect people living in crowded conditions. They’re different from head lice, which are far more common in the U.S. and typically affect school-age kids. Both insects feed on human blood.
“There’s a long-standing medical historical debate about the Black Death pandemic in Europe,” said senior author Joe Hinnebusch, who was a senior investigator at the National Institute of Allergy and Infectious Diseases Laboratory of Bacteriology in Hamilton, Montana, when the research was being performed. He is now retired.
Studies looking at the speed with which the plague spread in the Middle Ages have suggested that another blood-sucking bug might have played a role, Hinnebusch said.
The researchers first examined the possibility that human fleas — there are thousands of species of fleas and some specifically bite humans — could have helped spread the disease. It turned out that human fleas weren’t good at spreading the bacteria.