New DNA research into the evolution and spread of the plague has shown that during the first documented pandemic (AD 541-750) there were several different strains of the bacterium, Yersinia pestis, affecting different parts of Europe during different waves of the disease. The project also identified the earliest evidence of plague in Britain.
An international team of researchers analysed more than 180 samples from 21 sites across Europe, including in France, Britain, Germany, and Spain. In Britain, 22 samples came from Edix Hill cemetery near Barrington in southern Cambridgeshire, which dates from AD 500-650.
From all the samples, the team was able to reconstruct eight full genomes of Y. pestis, tripling the number of ancient genomes of the bacterium previously sequenced. They found seven different strains of the bacterium, four of which had not previously been identified. By comparing these new genomes with modern ones, they were able to determine that while the bacterium diversified quickly in Europe between the 6th and 8th centuries, all these strains stemmed from the same lineage, which probably evolved several hundred years prior to this in Central Asia. A more precise location could not be pinpointed, nor how the disease had spread, but the team hopes that further work in this area might help clarify matters.
One of the genomes that was successfully reconstructed came from the Edix Hill cemetery, and four of the 22 individuals sampled from the site tested positive for Y. pestis. This is the first concrete evidence of plague reaching the shores of Britain before the Black Death in the 14th century.
Craig Cessford from the University of Cambridge explained the significance of the discovery: ‘Although there are some relatively impressive burials, in most respects Edix Hill is broadly typical of inhumation cemeteries of the period from East Anglia. There are no documentary sources that definitely record that the Justinianic Plague of the 540s reached Anglo-Saxon England, so its identification at Edix Hill represents a major discovery. It is unlikely that this site is unusual in being affected by the plague; more probably most, if not all, of Anglo-Saxon England was ravaged by it.’
The results of the study were recent published in PNAS and can be found at https://doi.org/10.1073/pnas.1820447116.
