October 13, 2011
Black Death Genome Could Reveal Secrets of Ancient And Modern Pathogens
Scientists have successfully mapped the complete genome of the Black Death - the bubonic plague that wiped out 50 million Europeans between 1347 and 1351 and remains one of the most severe epidemics of all time - various news agencies reported on Wednesday.
According to Kate Kelland of Reuters, an international team of researchers extracted and purified DNA from the remains from victims buried in the so-called plague pits of London."Building on previous research which showed that a specific variant of the Yersinia pestis (Y. pestis) bacterium was responsible for the plague“¦ a team of German, Canadian and American scientists went on to 'capture' and sequence the entire genome of the disease," Kelland wrote.
"Their result -- a full draft of the entire Black Death genome -- should allow researchers to track changes in the disease's evolution and virulence, and lead to better understanding of modern-day infectious diseases," she added.
Kelland also noted that this information, combined with modern-day advances in DNA-related technology, should help discover a way to combat similar illnesses that exist today.
Surprisingly, says USA Today's Elizabeth Weise, the researchers discovered that the Y. pestis bacteria did not appear to be excessively "more virulent than the plague of today," leading them to believe that climate change, of all things, might have played a hand in the massive number of fatalities that resulted from the Black Death.
At the time, Europe was in the middle of an era of lower temperatures and increased rainfall known as the "Little Ice Age." The conditions at the time left people without enough food from harvests, meaning they did not have enough food to eat to keep their health up.
The cold, damp climate would also have been conducive to the rat population, which likely carried the blood-sucking parasites (believed to be fleas or lice) which helped the pathogen to spread more quickly,
"You had an immuno-compromised population living in London under stressful conditions who were then hit with a new pathogen," co-author Hendrik Poinar, an evolutionary geneticist at Canada's McMaster University, told Weise.
According to Kelland, an estimated 2,000 people each year are killed by illnesses that can be traced back to the Black Death, which lead researcher and University of Tuebingen professor Johannes Krause told AFP's Marlowe Hood was "the first plague pandemic in human history."
"Based on the reconstructed genome, we can say that the medieval plague is close to the root of all modern human pathogenic plague strains," Krause told AFP via email. "The ancient plague strain does not carry a single position that cannot be found in the same state in modern strains."
Along with Poinar and Krause, Kirsten Bos, Brian Golding and David Earn of McMaster University, Verena Schuenemann of the University of Tubingen, HernÃ¡n A. Burbano and Matthias Meyer of the Max Planck Institute for Evolutionary Anthropology, and Sharon DeWitte of the University of South Carolina, were among those who worked on the study, which has been published online in the journal Nature.
"The genomic data show that this bacterial strain, or variant, is the ancestor of all modern plagues we have today worldwide," Poinar said in a statement. "Every outbreak across the globe today stems from a descendant of the medieval plague“¦ With a better understanding of the evolution of this deadly pathogen, we are entering a new era of research into infectious disease."
"Using the same methodology, it should now be possible to study the genomes of all sorts of historic pathogens," added Krause. "This will provide us with direct insights into the evolution of human pathogens and historical pandemics."
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