Scientists Detect Smallpox Virus In Viking Skeletons
An international team of scientists has identified the presence of an extinct species of smallpox in the remnants of Viking skeletons from sites across northern Europe. Using multiple samples, they have reconstructed the almost complete genome of the variola virus (VARV) responsible for smallpox. Few days before the findings published in Science, another team of scientists had reported a study that identified the strains of smallpox virus that were circulating during the American Civil War.
By analyzing the DNA collected from viruses in the remains, the team found that the northern Europeans lived during the Viking Age, likely Vikings themselves were infected with extinct but related strains of the variola virus that causes smallpox. The findings suggest that the earliest smallpox cases appeared around 1000 years ago and plagued humanity for at least 1400 years. Previously, ancient traces of variola virus DNA were discovered by scientists in a mummy from the mid-1600s, which suggests the origin of variola virus strains occurred in the 16th or 17th centuries.
But it’s still not clear when did the virus start infecting people. Al least 500 million people have died from the infection, which is the only pathogen eradicated completely from the world. Scientists were able to find possible smallpox lesions on mummified remains and few 3,000 years old written records also have documented smallpox like symptoms. However, scientists noted that its difficult to claim that the smallpox virus was the cause of death.
Scientists now have a better idea about the devastating historical disease, and they are uncovering the diversity of the virus, which was unappreciated and unknown until now.
The viral DNA from the bones and teeth of 1,867 humans who lived approximately 31,000 to 150 years ago were collected by computational biologist Martin Sikora and his team. The remnants of the variola virus were found in 13 people among them. Eleven among them are likely to be Vikings who lived in the United Kingdom, Europe, and Russia around 1,000 years ago during the Viking Age. Remaining two are likely to be from western Russia from the 19th century.
The study revealed that the Viking-era strains belong to a now-extinct group of variola viruses, by reconstructing nearly complete genetic blueprints of four of the eleven ancient viruses. Sikora said smallpox might have spread throughout Europe, causing serious disease. It is also possible that Vikings who were infected spread the disease as they traveled.
The remnants of ancient smallpox virus DNA found in Viking skeletons could help uncover the extensive relationships of humans with pathogens even though the virus is gone now. Sikora added that the current COVID-19 pandemic is only the tip of the iceberg of pandemics the history has seen.