The earliest genetic evidence to date for copper virus dates back to the 17th century, but must now be traced back almost 1,000 years, according to an international research team led by the University of Copenhagen.
In a study in the scientific journal Science, they describe findings of the virus in the remains of eleven people from the Viking Age of Northern Europe (600 to 1050). The virus was widespread in society, the researchers believe.
The results may in the long term provide new answers to how a virus such as smallpox moves from animals to humans and how it mutates into a threat to humans.
– If anyone should be in doubt after the last few months, major epidemic diseases are something that can overthrow society. We can clearly use these findings to become better at dealing with some of the diseases that can affect society significantly, says archaeologist and DNA researcher Søren Michael Sindbæk to videnskab.dk.
Smallpox is one of the deadliest diseases that mankind has ever experienced and killed at least 500 million people alone in the 20th century. The last detected case of the copper virus was in Somalia in 1
The course of the disease is described as cruel and begins with a fever followed by a rash that develops into fluid-filled blisters. A successful vaccination campaign has led to the disease being declared eradicated.
To date, a mother from Lithuania has been the earliest find of copper. It dates from the 17th century, and it has since been claimed that the disease did not exist in Europe during the Middle Ages, but came here with knights from the Crusades in the Middle East.
Finds of the virus in the DNA material from eleven individuals from the Viking Age shake that story.
– We have positive results in Denmark, Sweden, northern Norway, Oxford in England and the European part of Russia. So it is a big spread, says Martin Sikora at the University of Copenhagen.
He points out that the researchers cannot determine that the eleven people died of copper. But there must have been high concentrations of the virus in humans, because it is possible to find it again so many years later.
Therefore, it is likely that several Vikings lost their lives due to the disease, the researchers believe. In total, the virus was detected in 2 percent of the residues examined.
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More deadly with time
Søren Michael Sindbæk believes that the results show that smallpox was a part of society, just as the flu is today, without causing mass death.
– In that case, one would find mass graves or very local eruptions. When the disease is widespread in many places, it indicates that people were exposed to it regularly, but did not die from it, he says.
Researchers have also been able to reconstruct more than 95 percent of the genome, or gene code, of the virus in the various bodies. This shows that the virus is of a different genetic variant, but from the same ancestor as the copper virus that ravaged during the 20th century.
As a result, researchers have been able to create a catalog of the genetic changes that the virus has undergone from the Viking Age to modern times.
– Many of the diseases that we as a society take most seriously today are those that first have a high mortality rate and against which we later develop higher immunity. But smallpox is an example of the opposite: the disease has become more deadly over time, says Sindbæk.