A researcher from the University of East Anglia has helped find the oldest case of the plague in Britain.

The team, led by the Francis Crick Institute, identified three 4,000-year-old British cases of Yersinia pestis, the bacteria causing the plague.

Working with the University of Oxford, the Levens Local History Group and the Wells and Mendip Museum, the team identified two cases of this bacteria in human remains found in a mass burial in Charterhouse Warren in Somerset and one in a ring cairn monument in Levens in Cumbria.

They took small skeletal samples from 34 individuals across the two sites, screening for the presence of the bacteria in teeth.

This technique is performed in a specialist clean room facility where they drill into the tooth and extract dental pulp, which can trap DNA remnants of infectious diseases.

They then analysed the DNA and identified three cases of Yersinia pestis in two children estimated to be aged between 10-12 years old when they died, and one woman aged between 35-45.

Radiocarbon dating was used to show it’s likely the three people lived at roughly the same time.

The plague has previously been identified in several individuals from Eurasia between 5,000 and 2,500 years ago, a period spanning the Late Neolithic and Bronze Age, but hadn’t been seen before in Britain at this point in time.

Dr Anders Bergström, from UEA’s School of Biological Sciences, said: “We knew from previous research that there was a Yersinia pestis lineage that was causing plague in continental Europe and Asia during the Bronze Age, a period that saw large-scale movements of people and cultural changes.

“But it had not been known whether the disease also reached Britain during this time, or whether people here might have been spared due to greater geographical isolation.

“The discovery in this study that Yersinia pestis had in fact reached Bronze Age Britain demonstrates how widely and quickly some pathogens could spread even in prehistoric human societies.”

This strain of the plague was likely brought into Central and Western Europe around 4,800 years ago by humans expanding into Eurasia, and now this research suggests that it extended to Britain.

Using genome sequencing, the researchers showed that this strain of Yersinia pestis looks very similar to the strain identified in Eurasia at the same time.

The individuals identified all lacked the yapC and ymt genes, which are seen in later strains of plague, the latter of which is known to play an important role in plague transmission via fleas.

This information has previously suggested that this strain of the plague was not transmitted via fleas, unlike later plague strains such as the one that caused the Black Death.

Because pathogenic DNA – DNA from bacteria, protozoa, or viruses which cause disease – degrades very quickly in samples which might be incomplete or eroded, it’s also possible that other individuals at these burial sites may have been infected with the same strain of plague.

The Charterhouse Warren site is rare as it doesn’t match other funeral sites from the time period – the individuals buried there appear to have died from trauma.

The researchers speculate that the mass burial wasn’t due to an outbreak of plague but individuals may have been infected at the time they died.

Pooja Swali, first author and PhD student at the Crick, said: “The ability to detect ancient pathogens from degraded samples, from thousands of years ago, is incredible.

“These genomes can inform us of the spread and evolutionary changes of pathogens in the past, and hopefully help us understand which genes may be important in the spread of infectious diseases.

“We see that this Yersinia pestis lineage, including genomes from this study, loses genes over time, a pattern that has emerged with later epidemics caused by the same pathogen.”

‘Yersinia pestis genomes reveal plague in Britain 4,000 years ago’  is published in the journal Nature Communications.