New discovery may rewrite history of smallpox

A new discovery in a Lithuanian crypt may rewrite the entire book on smallpox, according to a newly-published study. A report from McMaster University in Canada made public Thursday says that the virus may be thousands of years newer than recently thought.

The smallpox-carrying variola virus was once found on every inhabited continent on earth excepting Australia, and in Europe alone was responsible for hundreds of thousands of deaths a year. In the 18th century, British physician Edward Jenner discovered a way to inoculate against smallpox, creating the world's first vaccine and eradicating the highly-contagious disease worldwide by the 1970s. The virus now only exists as samples in secure labs for scientific research.

Smallpox has a particular sinister role in human history, with many holding it responsible for destroying Native American populations when they came into contact with Europeans.

Despite the virus' prevalence, however, its origins have remained mysterious. Scientists had previously suggested that pockmarked mummies as many as 3,000 years old from Ancient Egypt displayed signs of the disease, but Thursday's announcement calls this into question.

"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 Ana Duggan, first author of the study carried out by McMaster's Ancient DNA Center and published in the journal "Current Biology."

But the recent discovery of the variola virus in a 17th century child mummy from a Lithuanian crypt shows that the virus likely originated in humans between 1588 and 1645. This marks the oldest proven case of the virus in a human host.

According to Duggan, the new suggests "that the timeline of smallpox in human populations might be incorrect."

Earlier suspected cases possibly chicken pox

Co-author Henrik Poinar suggested that the earlier supposed cases of smallpox had been misidentified, and were more likely showing signs of the less deadly chicken pox.

The authors also wrote that the new evidence suggests that Jenner's vaccine made the virus split into two strains, changing the way it has affected humanity. Third co-author Edward Holmes of the University of Sydney in Australia suggested that far more research was necessary to discover how the virus ended up spreading amongst the human population in order to get the full picture of its affect on people.

"Our historical knowledge of viruses is just the tip of the iceberg," Holmes said.

es/se (AFP, dpa)