Smallpox May Be Relatively Recent in History

Eradication of smallpox is one of the shining lights of vaccination programs even when a certain poorly-informed subpool of Americans show no respect for that in their anti-vaxx campaigns.  (Science Daily:  17th Century strain of smallpox retrieved from partial mummified remains of Lithuanian child)

New genetic research from an international team including McMaster University, University of Helsinki, Vilnius University and the University of Sydney, suggests that smallpox, a pathogen that caused millions of deaths worldwide, may not be an ancient disease but a much more modern killer that went on to become the first human disease eradicated by vaccination.

- Science Daily

Here's why the contention smallpox is not such an old disease:

In an attempt to better understand its evolutionary history, and after obtaining clearance from the WHO in Geneva, scientists extracted the heavily fragmented DNA, from the partial mummified remains of a Lithuanian child believed to have died between 1643 and 1665, a period in which several smallpox outbreaks were documented throughout Europe with increasing levels of mortality.  The smallpox DNA was captured, sequenced and the ancient genome, one of the oldest viral genomes to date, was completely reconstructed. There was no indication of live virus in the sample and so the mummies are not infectious.

Researchers compared and contrasted the 17th Century strain to those from a modern databank of samples dating from 1940 up to its eradication in 1977.  Strikingly, the work shows that the evolution of smallpox virus occurred far more recently than previously thought, with all the available strains of the virus having an ancestor no older than 1580.

- Science Daily

America is an extremely young country and the smallpox is apparently even younger than that.  Here at the Rockhouse, we get a bang out of seeing researchers pursue their genome studies back millions of years but this one doesn't escape relatively-modern history.  I'm certainly not posing as an expert on the matter but I have not heard of such a thing before.

The researchers are specifically interested in how much immunization efforts had to do the deadliness of the disease.  This has nothing to do with harm coming to those who were vaccinated but rather it's in terms of increasing virulence toward those who were not.

One form of VARV (Variola virus), known as V. major was highly virulent and deadly, the other V, minor much more benign. However, scientists say, the two forms experienced a 'major population bottleneck' with the rise of global immunization efforts. The date of the ancestor of the minor strain corresponds well with the Atlantic Slave trade which was likely responsible for partial worldwide dissemination.

"This raises important questions about how a pathogen diversifies in the face of vaccination. While smallpox was eradicated in human populations, we can't become lazy or apathetic about its evolution -- and possible reemergence -- until we fully understand its origins," says Ana Duggan, a post doctoral fellow in the McMaster Ancient DNA Centre.

- Science Daily

As always, read the original science but, also as always, you will find it's not distorted on Ithaka;  there's more reading if it interests you.