Researchers have discovered Great Plague bacteria in the teeth of victims from the mass burial pit in East London.
The Great Plague outbreak in 17th century claimed over 100,000 lives in Britain, which was about a quarter of London's population in the 1650s. The archeologists unearthed a mass burial pit called a plague pit in Liverpool, while excavating the area to build a new Crossrail station in August 2015.
The researchers uncovered not just a few, but 3,500 burials in the pit. Samples from about 20 skeletons were taken and subjected to DNA analysis.
On analysis, the researchers at the Max Planck Institute in Germany discovered Yersinia pestis, the bacteria that cause plague, in five of the 20 teeth samples. The tooth enamel, which is considered the strongest substance in the human body, had preserved the bacterial DNA, keeping it intact, helping the researchers find answers to a long-held question.
"Ancient DNA is very vulnerable to contamination and suffers from full preservation. ... The teeth are like sealed capsules that preserve this information better than other parts of the skeleton," said Michael Henderson, Senior Human Osteologist at the Museum of London Archaeology, as reported by the Denver Channel.
Though records and evidence clearly indicate plague outbreak in the country, no traces of bacterial pathogens were isolated. Since the infection killed victims very quickly, no traces of the organism could be found on the bones.
Don Walker, Senior Human Osteologist at the Museum of London Archaeology, said that the discovery is significant because the causative agent behind the outbreak is unclear. Researchers who studied the Black Death, the first outbreak of plague in Britain in the middle of the 14th century, confirmed that Y. pestis was the organism behind the outbreak.
Now that the researchers have confirmed that the Great Plague was caused by Y. pestis, it looks like the outbreaks through the couple of centuries were caused by the same bacterium. Researchers doubted that the Great Plague could be different from Black Death because modern day plague is different from the disease suffered several centuries ago, Walker explained.
According to Walker, the modern plague is the third pandemic; though the infection is spread by rodents, it is not easily spread in humans. Comparing the DNA of modern plague with DNA from earlier outbreaks could help in better understanding the infection.
According to a World Health Organization report, about 126 deaths were recorded among 783 cases of plague worldwide in 2013.
Photo: Ralph Repo | Flickr
