- Title: NORWAY-PLAGUE DNA DNA research unlocks the secrets of the Black Death
- Date: 27th May 2015
- Summary: BERGEN, NORWAY (APRIL 29, 2015) (REUTERS) WIDE OF BERGEN HARBOUR VARIOUS OF HOMES BY HARBOUR VARIOUS OF BERGEN'S OLD WOODEN ALLEYWAYS AND HOMES WIDE OF HARBOUR OPPOSITE FROM HAAKONSHALLEN CASTLE PROFESSOR OF BIOLOGY AT UNIVERSITY OF OSLO, NILS STENSETH, LOOKING AT CASTLE (SOUNDBITE) (English) PROFESSOR OF BIOLOGY AT UNIVERSITY OF OSLO, NILS STENSETH, SAYING: "To Norway it came in the summer, early summer of 1349. It came to this very city and it came on a boat from England." CLOSE-UP OF CASTLE DOME (SOUNDBITE) (English) PROFESSOR OF BIOLOGY AT UNIVERSITY OF OSLO, NILS STENSETH, SAYING: "Now we can test that. We can look at skeletons from this period here in Bergen from the right time, as well as in Oslo, Krystiania at the same time, to see where these genes came from, where the Plague through the gene came from." OSLO, NORWAY (APRIL 27, 2015) (REUTERS) VARIOUS OF SENIOR RESEARCHER IN THEORETICAL BIOLOGY AT UNIVERSITY OF OSLO, BORIS SCHMID WITH RESEARCHER IN MOLECULAR ANTHROPOLOGY AT UNIVERSITY OF OSLO, BARBARA BRAMANTI, IN LABORATORY (SOUNDBITE) (English) SENIOR RESEARCHER IN MOLECULAR ANTHROPOLOGY AT UNIVERSITY OF OSLO, BARBARA BRAMANTI, SAYING: "Generally we try to collect some samples from these individuals. We prefer to work with teeth because in the teeth the DNA is better preserved than in the bones in our experience, particularly concerning the presence of pathogens."
- Embargoed: 11th June 2015 13:00
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- Topics: General
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- Story Text: Norwegian biologists studying the DNA of victims of the Black Death which killed up to 50 million people in the 14th Century hope their analysis could help predict the next plague outbreak, and perhaps help prevent a future global pandemic.
The team, led by Nils Stenseth, professor of biology at the University of Oslo (UiO), believe there is a direct relationship between climate change and the many major plague outbreaks throughout history.
Senior researcher in molecular anthropology Barbara Bramati, of the university's Centre for Ecological and Evolutionary Synthesis (CEES), is studying the evolutionary development of the plague bacteria and comparing the genetic code of the plague bacteria during the first two pandemics - the Black Death and the Justinian Plague, which occurred in the 6th Century.
The Black Death is particularly relevant to Norway. It arrived in rats on an English ship in the harbour of Bergen in 1349, eventually wiping out one third of Norway's population, Stenseth explained, standing next to the city port. "To Norway it came in the summer, early summer of 1349. It came to this very city and it came on a boat from England," said Stenseth.
In fact, the world's third major plague pandemic, which began in the late 18th Century in China and reached the rest of the world via Hong Kong, is technically still ongoing. Between last November and January 2015 an outbreak killed 71 people in Madagascar.
By analysing the DNA of Norway's Plague victims, Bramanti and her colleagues are seeking to discover where the plague bacterium comes from and how the plague bacterium survived between the outbreaks. "Now we can test that. We can look at skeletons from this period here in Bergen from the right time, as well as in Oslo, Krystiania at the same time, to see where these (plague) genes came from, where the plague through the gene came from," Stenseth explained.
Several studies have shown that the three plague pandemics were indeed the same disease, caused by the Yersinia pestis bacterium.
Bramati is finding some answers to the outstanding questions in the teeth of old skeletons. The lymph nodes of the plague victims swelled up and transformed into black boils, where the bacteria would multiply. In many victims the plague bacteria entered the bloodstream, and thus the dental pulp - the part in a tooth's centre consisting of living connective tissue and cells. Together with archaeologists, Bramanti is collecting DNA samples from the teeth of plague victims from Europe and Asia by drilling into the teeth and extracting the entire DNA content of the pulp.
"Generally we try to collect some samples from these individuals," explained Bramanti. "We prefer to work with teeth because in the teeth the DNA is better preserved than in the bones in our experience, particularly concerning the presence of pathogens."
She added: "Now we have very large number of samples coming from let's say Eurasia - from Europe from the first and second pandemic and also from some localities of Asia," she said.
The UiO's Department of Biosciences has opened a new DNA laboratory that makes it easier to analyse the DNA remnants.
While Bramanti's team concentrate on the genetic angle of the plague, theoretical biology researcher Boris Schmid is seeking to uncover potential links between climate change, the rise and fall of rodent populations, and plague outbreaks among them - and later humans.
Schmid says notable rises in temperature and/or rainfall, as recorded in tree rings in central Asia, have preceded previous plague outbreaks by about 15 years. "We saw these past climate patterns being preceding outbreaks in Europe every time by about 15 years in a consistent manner," said Schmid. "So then it was 'okay, here's a pattern we didn't expect'. We expected Plague to come to Europe once, settles inside rodents in Europe and then stay there for 400 years before it disappeared but now we find a pattern where Plague comes in again and again and it gives a way to explain how Plague persists in Europe without a reservoir, just by continuously being fed from Asia, driven by climate in Asia."
The Dutch researcher believes more plague outbreaks in Asia could follow, and without understanding why past outbreaks in Asia turned into global pandemics, the risk of a future one remains. "What kind of impact will it (global warming) have on synchronous sort of organised climate patterns in Asia? If it makes climate in Asia less constant and going in ups and downs you have more potential for plague outbreaks," he said.
Stenseth says statistical methodology developed in conjunction with colleagues from the United States, Noelle Samia and Kung-Sik Chan, showed how temperature rises could cause a rise in infected rodents. "Noelle Samia and Kung-Sik Chan they were able to develop new statistical methodology where we were able to show that and we were able to show that by increasing the Spring temperature by about one degree you double the incidence, you double the frequencies as you say of infected rodents. So we were able to show that. That was sort of the first climate effect."
It remains unclear how the Black Death spread, although it has traditionally been blamed on either rats or fleas. Fellow researchers at a plague laboratory in China who have been injecting plague bacteria into gerbils, who appear to handle the contagion surprisingly well. More than half the rodents survived the bacterium, allowing researchers to compare their genomes with those that died. They hope to find a genetic explanation as to why the gerbils' immune systems are so strong against the plague bacterium and are seeking to fully sequence the gerbil's genome. The researchers believe that protection against plague is related to a hereditary congenital immune system.
Stenseth insists the multi-faceted research is far from abstract. He said: "My motivation for doing this is really to find out how things work, simply curiosity but this curiosity is also very important in understanding when there might be a plague outbreak among people. We can say that. We can say that because if there has been a large population for a couple of years of gerbils over a large area and it suddenly crashes, that's the time when it's going to spill over, so this is really of direct interest to public health people."
There are 2,000 cases of plague annually, mostly in Madagascar and Congo, while it also occurs in the deserts of North America and in large areas of Central Asia. - Copyright Holder: FILE REUTERS (CAN SELL)
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