New Finding Shows Smallpox Is Not An Ancient Disease

Smallpox, a disease caused by the variola virus declared eradicated in 1980, is much younger a disease than previously thought. The origins of smallpox placed the disease thousands of years in the past, believed to have emerged during the times of Ancient Egypt, with the disease appearing in India and China (some historical reports suggest Ramses V, an Egyptian pharaoh who passed away in 1145 B.C, suffered from the disease). The findings of a recent study show smallpox are much younger, originating just a couple of hundreds of years ago.

Location Where Mummy Is Found
Location Where Mummy Is Found

A study, which analyzed the viral DNA taken from a mummified remains of a child from Lithuania, dating back from the 17th century gave some interesting results. Researchers managed to capture, sequence and reconstruct the viral smallpox DNA; the reconstructed DNA sample then got compared with modern samples dating between1940 and 1977 (the sample from 1977 was from Somalia where the last known case of the disease occurred before being officially eradicated in 1980).

The child likely died between 1643 and 1665, a time period when Europe faced against several major smallpox outbreaks. Scientist obtained clearance from WHO (World Health Organization) based in Geneva, allowing them to extract a fragmented DNA taken from the child. The comparison showed that the evolution of smallpox happened more recently than previously thought.

Instead of putting the smallpox evolution thousands of years back into the past, new findings show the ancestor of all available smallpox strains is no older than 1580. Although scientists were able to date the viral strain, it is still unknown what kind of animal carried the virus, and when the first jump from an animal to a human happened. The study did find that the virus evolved into to circulating strains (variola major and variola minor) after 1796, after Edward Jenner, a famous scientist, made a vaccine.

The researchers wrote that “Our data clearly show that the VARV lineages eradicated during the 20th century had only been in existence for ∼200 years, at a time of rapidly expanding the human movement and population size in the face of increasingly widespread inoculation and vaccination.”

Smallpox got eradicated back in 1980, with the WHO allowing only two laboratories to store samples of the virus (one in Atlanta in the U.S, the other in Russia); both repositories are inspected on a regular basis by the WHO.