Bringing Back the Black Plague?

November 1st, 2011 by Andrea Bennett

Is it risky to re-create the genetic sequence of an epidemic?

Brought to you by Liberty Mutual's
The Responsibility Project

Thought the Black Death ended in the 14th century? Well it’s back, but this time it’s confined to a lab.

A recent report in Nature details the efforts of a team of German, Canadian and U.S. scientists to reconstruct the genetic sequence of the Black Plague. Between 1347 and 1351, the epidemic took between 30 and 50 million lives – up to half of Western Europe’s population at the time – and today scientists are reexamining why.

A BBC story on the research describes how scientists were able to find a strain of the disease by extracting dried blood from the teeth of four 14th-century plague victims exhumed from a London graveyard. The microbe’s DNA was in lousy shape, notes a Time magazine story, as it had blended with its hosts’ genomes and the genes of bacteria degrading in the bodies for over 600 years. However, through a variety of new techniques, researchers isolated the “plague DNA,” cleaned it and sequenced it. The feat is widely considered a major scientific achievement; The New York Times even called it a “technical tour de force.”

So why go digging for a disease buried for over six centuries? For one, the process of isolating the plague DNA will be used as a model to re-create the pathogens that caused other ancient epidemics. A more pressing reason, according to Johannes Krause of the University of Tübingen in Germany, a co-author of the study, was to resolve a scientific debate. In his interview with the BBC, Krause explains that for years, there had been two schools of thought: those who argued that modern strains of the plague bacterium, Yersinia pestis, were descended from the Black Death, and those who argued that a different bug caused the 14th century plague. "It turns out that this ancient Yersinia pestis strain is very close to the common ancestor of all modern strains that can infect humans," he said. "It's the grandmother of all plague that's around today."

However, according to the study’s other lead author, Kirsten I. Bos of McMaster University, there is one key factor that sets the Black Death apart from modern strains: the living conditions of the day. Bos told the Times that the overwhelming deadliness of the plague likely reflected a cooling climate, heavy rains that rotted crops and caused famines, and the effects of the Hundred Years’ War that broke out in 1337. Bos noted in her interview that people saw the plague as, “the fourth horseman of the apocalypse. People honestly thought it was the end of the world.”

And for those concerned about the potential release of a super bug on the modern world, the Times story quotes Northern Arizona University infectious bacteria specialist Paul Keim: “It is really easy to break the transmission cycle with antibiotics and public health” in modern times. And to emphasize the point, Keim noted, “A multiyear large human outbreak is inconceivable in this day.”

What do you think of the research on the Black Death? Is it our responsibility to understand the history of public health so that we aren’t “doomed to repeat it”?