In 14th century Europe, the plague known as the Black Death swept through the continent killing between 30 to 60 percent of Europe's population. The symptoms were swift and terrible and included painful swellings (buboes) of the lymph nodes that could reach the size of an apple.
Buboes appeared in the armpits, neck, legs, or groin of those infected. They began red in color but progressed to a dark purple or black, thus the name “Black Death.” Infected individuals experienced a very high fever, delirium and vomiting of blood. Victims died quickly, living only 2 to 4 days after contracting the disease.
In the wake of the pandemic, the world's population was reduced from about 450 million to between 350 and 374 million. It took Europe over a century to recover. Though it returned from time to time, the plague left Europe in the 19th century and is now extinct.
Or is it? Modern forms of the Black Death.
Researchers report that the particular version of plague caused by the bacteria Yersinia pestis is gone, but other deadly forms are alive and well today. A new study examined the DNA from more than 100 plague victims of London buried between 1348 and 1350 and found evidence of a strain of Y. pestis. The researchers, led by Hendrik N. Poinar of McMaster University in Canada, and Johannes Krause of Tuebngen University in Germany wrote, "Our data reveal that the Black Death in medieval Europe was caused by a variant of Y. pestis that may no longer exist".
While that is certainly reassuring, it doesn't mean we can sit back and relax. There are other forms of the bacteria that are dangerous, and just like the Black Death, are carried by fleas. Plague no longer causes sweeping deaths because it is relatively easy to keep at bay with antibiotics
, isolation and pesticides. However, since 1954, Brazil, Madagascar, Congo, Myanmar, Vietnam, and the U.S. have seen yearly outbreaks.
Virginia Miller of the University of North Carolina's Center for Infectious Disease said she wasn't surprised to find that the research findings reconfirmed that the Black Death was caused by a variant of Y. pestis after all. Other researchers questioned whether the bacterium was behind the pandemic in the 1970s and 1980s, but this latest report reaffirms Y. pestis as the cause.
According to Poinar, “With any ancient pathogen, understanding why it might have been so virulent in the past is important to be able to predict possible reemergence today. If it did, perhaps we might be prepared.”