Controversial new research suggests that contrary to the history books, the "Black Death" that devastated medieval Europe was not the bubonic plague, but rather an Ebola-like virus.
History books have long taught the Black Death, which wiped out a quarter of Europe's population in the Middle Ages, was caused by bubonic plague, spread by infected fleas that lived on black rats. But new research in England suggests the killer was actually an Ebola-like virus transmitted directly from person to person.
The Black Death killed some 25 million Europeans in a devastating outbreak between 1347 and 1352, and then reappeared periodically for more than 300 years. Scholars had thought flea-infested rats living on ships brought the disease from China to Italy and then the rest of the continent.
But researchers Christopher Duncan and Susan Scott of the University of Liverpool say that the flea-borne bubonic plague could not have torn across Europe the way the Black Death did.
"If you look at the way it spreads, it was spreading at a rate of around 30 miles in two to three days," says Duncan. "Bubonic plague moves at a pace of around 100 yards a year."
Unlike the bubonic plague, a bacterial disease which still exists in parts of Asia, India and North America, viral diseases are passed on from person to person, usually by breath or touch.
Ebola-Like Symptoms Cited
In their new book Biology of Plagues: Evidence from Historical Populations, Duncan and Scott compare the signs and symptoms of the Black Death with modern-day viruses such as the Spanish flu, the West Nile virus and, most closely, Ebola.
Medieval descriptions of the Black Death sound like the hemorrhagic fever caused by an Ebola-like virus, the authors say. Such fever strikes fast and causes blood vessels to burst underneath the skin, bringing out welts, similar to what British medical texts from the Middle Ages describe as "God's tokens."
The liquidization of internal organs that causes excruciating pain in Ebola victims matches the descriptions of historical autopsies on plague victims, which similarly describe internal organs being dissolved along with the appearance of a black liquid, according to the authors.
Duncan and Scott also note that efforts to quarantine the Black Death were successful. In the wake of the first outbreak, Europeans learned that quarantining infected families for 40 days was effective in stopping the spread. Such a measure would not have worked if the disease were transmitted by rats, the authors suggest, because rats do not observe quarantines.
Also, the 40-day period was enough time to ensure the disease finished its incubation period. One of the difficulties in controlling the Ebola virus is that its symptoms start to appear only about five to 22 days after exposure. Therefore people who appear perfectly healthy could be carrying the lethal disease.
Skeptics Say Theorists Should Work Plague by Plague
Ann Carmichael, a historian who is an expert on the Black Plague, welcomes the work produced by Duncan and Scott, but remains skeptical.
"It is problematic to assimilate evidence over four centuries and draw conclusive theories," says Carmichael. "We must look at it on a plague-by-plague basis."
According to Carmichael, texts dating from 14th-century Italy provide extremely detailed and consistent accounts that describe visible swellings called buboes that developed predominantly under the skin around the groin and armpits — a prime target area for fleas. The buboes are what give bubonic plague its name.
"We don't know that Florentine buboes looked like 'God's tokens' found in England, however," she says.
The research by Duncan and Scott is a good start, but there is need for further research, says Carmichael. There is no robust evidence that quarantining systematically applied worked, she says.
Link to HIV-Resistant Gene?
Duncan and Scott believe their theory of a viral cause for the Black Death is supported by the recent discovery of a mutated gene called CCR5 that is resistant to HIV/AIDS. It is estimated that approximately 10 percent to 18 percent of those of European descent carry the gene.
American researchers working on the gene have calculated that the first mutation of the gene took place around 650 years ago — coinciding with the first outbreak of the Black Death in Europe.
According to Duncan, a process of natural selection could have left Europe populated predominantly by those carrying the mutated gene. This would account for the high percentage of the European population that still carries this gene.