Post by Admin on Feb 25, 2023 21:50:22 GMT
Ancient DNA Sheds Light on Spread of Plague in Medieval Denmark
Feb 24, 2023
By analyzing DNA obtained from fragments of ancient teeth, a team of led by scientists from McMaster University has gained new insights into the evolution of the plague over hundreds of years in medieval Denmark. The plague, caused by the bacterium Yersinia pestis, is responsible for several devastating pandemics across Europe, Asia, and Africa during the Middle Ages. Its historical epidemiology, however, is controversial due to the scarcity and ambiguity of available data. To better understand the disease's spread in Scandinavia, the researchers performed in-depth longitudinal screening for Y. pestis across archaeological sites in Denmark, identifying the bacterium's DNA in tooth samples from 13 individuals who lived at different times between the 14th and 17th centuries. As reported in Current Biology this week, they used the DNA to reconstruct and analyze Y. pestis genomes, revealing the continual evolution and reintroduction of bacterial strains throughout waves of plague infections. The analysis, the study's authors write, shows that the Danish Y. pestis sequences were "interspersed with those from other European countries rather than forming a single cluster, indicative of the generation, spread, and replacement of bacterial variants through communities rather than their long-term local persistence. These results provide an epidemiological link between Y. pestis and the unknown pestilence that afflicted medieval and early modern Europe," as well as highlight the utility of population-scale genomic evidence for historical disease research, they add.
Emergence, continuity, and evolution of Yersinia pestis throughout medieval and early modern Denmark
Summary
The historical epidemiology of plague is controversial due to the scarcity and ambiguity of available data. 1 ,2 A common source of debate is the extent and pattern of plague re-emergence and local continuity in Europe during the 14th–18th century CE. 3 Despite having a uniquely long history of plague (∼5,000 years), Scandinavia is relatively underrepresented in the historical archives. 4 ,5 To better understand the historical epidemiology and evolutionary history of plague in this region, we performed in-depth (n = 298) longitudinal screening (800 years) for the plague bacterium Yersinia pestis (Y. pestis) across 13 archaeological sites in Denmark from 1000 to 1800 CE. Our genomic and phylogenetic data captured the emergence, continuity, and evolution of Y. pestis in this region over a period of 300 years (14th–17th century CE), for which the plague-positivity rate was 8.3% (3.3%–14.3% by site). Our phylogenetic analysis revealed that the Danish Y. pestis sequences were interspersed with those from other European countries, rather than forming a single cluster, indicative of the generation, spread, and replacement of bacterial variants through communities rather than their long-term local persistence. These results provide an epidemiological link between Y. pestis and the unknown pestilence that afflicted medieval and early modern Europe. They also demonstrate how population-scale genomic evidence can be used to test hypotheses on disease mortality and epidemiology and help pave the way for the next generation of historical disease research.
Feb 24, 2023
By analyzing DNA obtained from fragments of ancient teeth, a team of led by scientists from McMaster University has gained new insights into the evolution of the plague over hundreds of years in medieval Denmark. The plague, caused by the bacterium Yersinia pestis, is responsible for several devastating pandemics across Europe, Asia, and Africa during the Middle Ages. Its historical epidemiology, however, is controversial due to the scarcity and ambiguity of available data. To better understand the disease's spread in Scandinavia, the researchers performed in-depth longitudinal screening for Y. pestis across archaeological sites in Denmark, identifying the bacterium's DNA in tooth samples from 13 individuals who lived at different times between the 14th and 17th centuries. As reported in Current Biology this week, they used the DNA to reconstruct and analyze Y. pestis genomes, revealing the continual evolution and reintroduction of bacterial strains throughout waves of plague infections. The analysis, the study's authors write, shows that the Danish Y. pestis sequences were "interspersed with those from other European countries rather than forming a single cluster, indicative of the generation, spread, and replacement of bacterial variants through communities rather than their long-term local persistence. These results provide an epidemiological link between Y. pestis and the unknown pestilence that afflicted medieval and early modern Europe," as well as highlight the utility of population-scale genomic evidence for historical disease research, they add.
Emergence, continuity, and evolution of Yersinia pestis throughout medieval and early modern Denmark
Summary
The historical epidemiology of plague is controversial due to the scarcity and ambiguity of available data. 1 ,2 A common source of debate is the extent and pattern of plague re-emergence and local continuity in Europe during the 14th–18th century CE. 3 Despite having a uniquely long history of plague (∼5,000 years), Scandinavia is relatively underrepresented in the historical archives. 4 ,5 To better understand the historical epidemiology and evolutionary history of plague in this region, we performed in-depth (n = 298) longitudinal screening (800 years) for the plague bacterium Yersinia pestis (Y. pestis) across 13 archaeological sites in Denmark from 1000 to 1800 CE. Our genomic and phylogenetic data captured the emergence, continuity, and evolution of Y. pestis in this region over a period of 300 years (14th–17th century CE), for which the plague-positivity rate was 8.3% (3.3%–14.3% by site). Our phylogenetic analysis revealed that the Danish Y. pestis sequences were interspersed with those from other European countries, rather than forming a single cluster, indicative of the generation, spread, and replacement of bacterial variants through communities rather than their long-term local persistence. These results provide an epidemiological link between Y. pestis and the unknown pestilence that afflicted medieval and early modern Europe. They also demonstrate how population-scale genomic evidence can be used to test hypotheses on disease mortality and epidemiology and help pave the way for the next generation of historical disease research.