Child Mummy Sheds Light on the History of Smallpox

Smallpox virus DNA has been extracted from this mummy found in a church crypt in Lithuania. Photo Credit: Kiril Čachovskij.

Smallpox viral DNA found in a mummy of a boy who lived in the 17th century in Lithuania is changing our modern day understanding of the history of the disease.

Scientists gathered the relatively intact viral strain from the mummy’s preserved tissues — the oldest known sample of smallpox — and ran tests on the sample. They discovered the disease may be a lot more modern than previously thought.

The mummy lies in a crypt under a Lithuanian church discovered recently, noted the authors of the study that appeared in the Dec. 8 issue of Current Biology.

“There have been signs that Egyptian mummies that are 3,000 to 4,000 years old have pockmarked scarring that have been interpreted as cases of smallpox,” said author Ana Duggan, a postdoctoral fellow at the McMaster University Ancient DNA Center in Canada.

“The new discoveries really throw those findings into question, and they suggest that the timeline of smallpox in human populations might be incorrect,” she added.

The team of scientists collected the virus, or variola, from DNA of the child’s skin. Tests of the sample revealed the viral strain matches samples from the mid-1900s and the late 1970s.

The samples all indicated the viral strain dates back to the years 1588-1645, when humanity was criss-crossing the world in great exploratory trips that incidentally helped spread the disease across the planet, the researchers said.

“So now that we have a timeline, we have to ask whether the earlier documented historical evidence of smallpox, which goes back to Ramses V and includes everything up to the 1500s, is real,” said study co-author Hendrik Poinar, the director of the Ancient DNA Center at McMaster University in Canada.

“Are these indeed real cases of smallpox, or are these misidentifications, which we know is very easy to do, because it is likely possible to mistake smallpox for chicken pox and measles,” he said.

Despite the revelations of the smallpox strain captured from the mummified child’s remains, scientists have yet to pinpoint the origin of the disease.

“Now we know all the evolution of the sampled strains dates from 1650, but we still don’t know when smallpox first appeared in humans, and we don’t know what animal it came from, and we don’t know that because we don’t have any older historical samples to work with,” said study co-author Edward Holmes, a professor at the University of Sydney in Australia. “So this does put a new perspective on this very important disease.”