Patient zero?

Oldest-known bubonic plague victim revealed.

Pictured here is the upper part of the skull of RV 2039, a hunter-gatherer male who lived some 5,000 years ago in the Rinnukalns area of modern Latvia. He was discovered during the late 1800s, together with another skeleton. Two more burials came from the site in 2011, most likely members of the same band. The University of Keil has now used samples from the teeth and bone of all four skeletons to sequence their genomes, and also tested the samples for bacterial and viral pathogens. To their astonishment, they found evidence of Yersinia pestis in RV2039.

This is the earliest example of the bubonic plague bacteria yet discovered. However, this ancient strain of Y. pestis lacked a key gene that made the Black Death strain of the plague so deadly in 14th century Europe. This gene allows fleas to act as vectors to spread the plague to human hosts, resulting in the pus-filled buboes (swollen lymph nodes) that affected medieval victims.

It took more than a thousand years for Y. pestis to acquire the mutations that allowed flea-based transmission. RV 2039 had the bacteria in his bloodstream, but the people buried nearby were not infected. Furthermore, he was buried carefully and methodically, apparently not in a hurry. This makes it unlikely that he was infected with a highly infectious version of the plague. Most likely, an infected rodent bit RV2039, the disease moved fairly slowly, and probably did not infect other people in the band.

Research published in the journal Cell Reports (June 2021). Image by Dominik Göldner, BGAEU, Berlin.