by Carla Murez
Health Day Reporter
WEDNESDAY, Jan. 11, 2023 (HealthDay News) — While the origin of smallpox has been a mystery for centuries, researchers now believe it’s 2,000 years older than previously thought.
Until recently, the earliest genetic evidence for variola virus (variola virus) came from the 1600s. In 2020, researchers found evidence of it in the dental remains of Viking skeletons, pushing its existence back by 1,000 years.
Now, Italian scientists have used mathematical equations to determine the origin of smallpox, and combined with pockmarks seen on ancient Egyptian mummies, they have pushed back the emergence of the virus by 3,800 years.
“Varola virus may be much older than we thought,” said lead author Dr Diego Forni from the IRCCS Eugenio Medea Scientific Institute in Italy.
“This is important because it confirms the historical assumption that smallpox existed in ancient societies. It is also important to consider that certain aspects of viral evolution should be taken into account when doing such work,” Forni said in a press release from the Society for Microbiology Said at the meeting.
Smallpox, which was only recently eradicated, killed at least 300 million people in the 20th century, relatively speaking.
In the new study, the researchers found that different smallpox strains all originated from a common ancestor. A small subset of genetic components found in the Viking Age genome even survived into the 18th century.
To estimate the origin of the virus, the researchers then explained a phenomenon called the “time-dependent rate phenomenon.”
This means that the rate of evolution depends on the length of time over which it is measured. According to the study authors, this means that viruses appear to change more rapidly over short periods of time and more slowly over longer timescales, as is well documented in DNA viruses.
Using mathematical equations to explain the rate of change over time, the team estimated that smallpox may have first appeared in Egyptian times: ancient mummies, including pharaoh Ramses V, who died in 1157 B.C., had suspicious scars .
The findings were published online Jan. 9 in the journal Microbial Genomics.
The U.S. Centers for Disease Control and Prevention has more information on smallpox.
Source: Society for Microbiology, press release, January 9, 2023