Medieval Plague Bacteria Probably Extinct
OK, this is cool. At least for microbiology geeks. A group of researchers compared plasmid DNA from Y. pestis collected from victims of The Black Plague (~1300s) to modern variants of the same bacteria. They found completely different sequences and discovered a completely new, previously unreported variant in the Medieval samples.
Text from the CNN article:
Modern outbreaks - swine flu, bird flu, SARS - have been scary and deadly, but they don't hold a candle to a plague called the Black Death. The disease killed an estimated one-third of Europe's population, perhaps 100 million people.
It's been a while, but scientists are now figuring out what caused the Black Death - at least, the one that swept through Europe from 1347 to 1351. They found evidence of the bacterium Yersinia pestis in the teeth of some of the medieval victims of the plague. Results are published in the Proceedings of the National Academy of Sciences.
Researchers screened more than 100 skeletal remains dating from 1348 to 1350 in the East Smithfield mass burial site, located in London, a place where plague victims were known to be buried.
They found a variation of Yersinia pestis that may no longer exist, as it has never been previously reported, study authors said. That suggests that this did not result from contamination from modern bacteria.
There had been some debate about whether there was some other explanation for the medieval plague, such as a different pathogen or bacteria.
The medieval plague is considered the second of three - the first was the Plague of Justinian in 541 A.D., and the third was noted in the 20th century; that disease represents about 2,000 cases per year, worldwide, on average.
A different form of Yersinia pestis is considered the cause of the plague that still exists today. As in the days of knights and castles, modern outbreaks of plague are associated with infected rats and rat fleas, according to the Centers of Disease Control and Prevention.
In the United States, plague cases in humans mostly occur in parts of New Mexico, Arizona, Colorado, California, Oregon and Nevada. Internationally, it can be found in Africa, Asia and South America. The plague can still be deadly without proper care, but antibiotics can fight it off.
Given that the World Health Organization has said that plague is a "reemerging infectious disease," further study of the spread of the older version may be worthwhile.
Link.
And the abstract from the PNAS paper:
Although investigations of medieval plague victims have identified
Yersinia pestis as the putative etiologic agent of the pandemic,
methodological limitations have prevented large-scale
genomic investigations to evaluate changes in the pathogen’s virulence
over time. We screened over 100 skeletal remains from
Black Death victims of the East Smithfield mass burial site (1348-
1350, London, England). Recent methods of DNA enrichment coupled
with high-throughput DNA sequencing subsequently permitted
reconstruction of ten full human mitochondrial genomes (16
kb each) and the full pPCP1 (9.6 kb) virulence-associated plasmid
at high coverage. Comparisons of molecular damage profiles between
endogenous human and Y. pestis DNA confirmed its authenticity
as an ancient pathogen, thus representing the longest
contiguous genomic sequence for an ancient pathogen to date.
Comparison of our reconstructed plasmid against modern Y. pestis
shows identity with several isolates matching the Medievalis biovar;
however, our chromosomal sequences indicate the victims
were infected with a Y. pestis variant that has not been previously
reported. Our data reveal that the Black Death in medieval Europe
was caused by a variant of Y. pestis that may no longer exist, and
genetic data carried on its pPCP1 plasmid were not responsible for
the purported epidemiological differences between ancient and
modern forms of Y. pestis infections.
Text from the CNN article:
Modern outbreaks - swine flu, bird flu, SARS - have been scary and deadly, but they don't hold a candle to a plague called the Black Death. The disease killed an estimated one-third of Europe's population, perhaps 100 million people.
It's been a while, but scientists are now figuring out what caused the Black Death - at least, the one that swept through Europe from 1347 to 1351. They found evidence of the bacterium Yersinia pestis in the teeth of some of the medieval victims of the plague. Results are published in the Proceedings of the National Academy of Sciences.
Researchers screened more than 100 skeletal remains dating from 1348 to 1350 in the East Smithfield mass burial site, located in London, a place where plague victims were known to be buried.
They found a variation of Yersinia pestis that may no longer exist, as it has never been previously reported, study authors said. That suggests that this did not result from contamination from modern bacteria.
There had been some debate about whether there was some other explanation for the medieval plague, such as a different pathogen or bacteria.
The medieval plague is considered the second of three - the first was the Plague of Justinian in 541 A.D., and the third was noted in the 20th century; that disease represents about 2,000 cases per year, worldwide, on average.
A different form of Yersinia pestis is considered the cause of the plague that still exists today. As in the days of knights and castles, modern outbreaks of plague are associated with infected rats and rat fleas, according to the Centers of Disease Control and Prevention.
In the United States, plague cases in humans mostly occur in parts of New Mexico, Arizona, Colorado, California, Oregon and Nevada. Internationally, it can be found in Africa, Asia and South America. The plague can still be deadly without proper care, but antibiotics can fight it off.
Given that the World Health Organization has said that plague is a "reemerging infectious disease," further study of the spread of the older version may be worthwhile.
Link.
And the abstract from the PNAS paper:
Although investigations of medieval plague victims have identified
Yersinia pestis as the putative etiologic agent of the pandemic,
methodological limitations have prevented large-scale
genomic investigations to evaluate changes in the pathogen’s virulence
over time. We screened over 100 skeletal remains from
Black Death victims of the East Smithfield mass burial site (1348-
1350, London, England). Recent methods of DNA enrichment coupled
with high-throughput DNA sequencing subsequently permitted
reconstruction of ten full human mitochondrial genomes (16
kb each) and the full pPCP1 (9.6 kb) virulence-associated plasmid
at high coverage. Comparisons of molecular damage profiles between
endogenous human and Y. pestis DNA confirmed its authenticity
as an ancient pathogen, thus representing the longest
contiguous genomic sequence for an ancient pathogen to date.
Comparison of our reconstructed plasmid against modern Y. pestis
shows identity with several isolates matching the Medievalis biovar;
however, our chromosomal sequences indicate the victims
were infected with a Y. pestis variant that has not been previously
reported. Our data reveal that the Black Death in medieval Europe
was caused by a variant of Y. pestis that may no longer exist, and
genetic data carried on its pPCP1 plasmid were not responsible for
the purported epidemiological differences between ancient and
modern forms of Y. pestis infections.