Smallpox was an infectious disease caused by either of two virus variants, Variola major and Variola minor. The disease is now considered to be eradicated in 1980, as a result of a concentrated global effort; the last naturally occurring case in the world was in Somalia in 1977, as outlined in The Sage Encyclopedia of Pharmacology and Society. The infection of the skin gave rise to a characteristic maculopapular rash, which accounts for the origins of the name of the virus.
Although all natural forms of the disease are gone, following eradication some stocks of smallpox were transferred to two WHO reference laboratories (CDC in Atlanta and one at the State Research Center of Virology and Biotechnology (VECTOR) in Novosibirsk, Russia). The disease remains under careful security in these locations in case to prevent its use as a bio-terror weapon.
Smallpox is commonly believed to have emerged in human populations about 10,000 BCE, although a new report now casts doubt on this assumption. The reason why smallpox is considered to be an ancient disease relates to pustular rashes on the mummified body of Pharaoh Ramses V of Egypt (1149–1145 BCE) and speculation that the disease is much older.
Now researchers think smallpox has only been around for hundreds rather than thousands of years. This relates to an analysis of viral DNA taken from the mummified remains of a child living during the 17th Century (found in a crypt of a church in Vilnius, Lithuania.) Here a researcher from the University of Sydney, Dr. Edward Holmes stated: “We managed to sequence the complete genome of the virus that causes smallpox, that’s called variola virus …. It’s the oldest human virus ever sequenced.”
Matching the analysis with radiocarbon dating, the child lived about 1650 CE, when smallpox was prevalent in Europe. This tells researchers that the evolutionary history of the virus is far more recent than previously thought before, seemingly making it only hundreds of years old. The scientists constructed a family tree using 49 modern strains of smallpox and the child’s ancient one. With this they were able to trace the evolution of all strains back to a common ancestor, and this ancestral virus is dated between 1530 and 1654 CE. This then leads to the question: how did smallpox arise and what did the virus evolve from?
The inference is that the observations of physical signs of pustular rashes on Egyptians and the like could well have been different diseases. Although further evidence will be needed to determine whether or not smallpox existed before the seventeenth century or if similar types of killer viruses were present.
The research is published in the journal Current Biology, with the paper titled “17th Century Variola Virus Reveals the Recent History of Smallpox.”
