extinct strains of smallpox in the teeth of Viking skeletons
Scientists have discovered extinct strains of smallpox in the teeth of Viking skeletons — proving for the first time that the killer disease plagued humanity for at least 1400 years.
Smallpox spread from person to person via infectious droplets, killed around a third of sufferers, and left another third permanently scarred or blind. Around 300 million people died from it in the 20th century alone before it was officially eradicated in 1980 through a global vaccination effort — the first human disease to be wiped out.
Now an international team of scientists has sequenced the genomes of newly discovered strains of the virus after it was extracted from the teeth of Viking skeletons from sites across northern Europe. The findings have been published in Science today (July 23, 2020).
Professor Eske Willerslev, of St John’s College, University of Cambridge, and director of The Lundbeck Foundation GeoGenetics Centre, University of Copenhagen, led the study.
“The 1400-year-old genetic information extracted from these skeletons is hugely significant because it teaches us about the evolution of the variola virus that caused smallpox.”
Historians believe smallpox may have existed since 10,000 BC, but there was no scientific proof that the virus was present before the 17th century. It is unknown how it first infected humans but, like Covid-19, it is believed to have come from animals.
Professor Martin Sikora, one of the senior authors leading the study, from the Centre for GeoGenetics, University of Copenhagen, said: “The timeline of the emergence of smallpox has always been unclear, but by sequencing the earliest-known strain of the killer virus, we have proved for the first time that disease existed during the Viking Age.
“While we don’t know for sure if these strains of smallpox were fatal and caused the death of the Vikings we sampled, they certainly died with smallpox in their bloodstream for us to be able to detect it up to 1400 years later. It is also highly probable there were epidemics earlier than our findings that scientists have yet to discover DNA evidence of.”