Syphilis in Ancient Bone

Researchers working on the syphilis disease are using a novel way to extract samples of this tricky customer- by looking for them in ancient fossils.

The bacterium causing this disease— Treponema pallidum pallidum — is exceptionally hard to isolate because of similarity with other members of its species (Treponena pallidum — the second pallidum in its name refers to the subspecies it belongs to). It also refuses to grow outside organisms, even in nutrient-rich lab conditions. The only way scientists have been able to grow it is when they directly transfer it from the tissue of one organism to another which is cumbersome, expensive, and probably not a very pleasant experience for the mice involved.

Photo Credit: Universitat Autònoma de Barcelona
Bone lesions of these fossils show bacteria in them

Bacteria in Fossils

And thus did the obscure field of Paleopathology (the science of diseases in ancient remains) come into the picture. Scientists at the University of Barcelona have found that fossils of newborns have remarkably good quality preserves of syphilis DNA (the fossils are undated as of now). This is easy to identify because the genome sequence of the bacterium is known, and all that is needed is a match query that will fix the identity of the sample. Newborns with congenital syphilis have a greater concentration of bacteria in their bones which keeps it preserved for longer periods of time.

Looking for Evolutionary Insights
It should be noted that this does not circumvent the problematic isolation of the bacterial organism. However, this discovery could give more insights into the history of the disease and the evolution of the bacterium over time. This field, in fact, could yield exciting information about the evolutionary race between pathogens and humans. Are pathogenic species evolving smartly to better evade the defenses offered by the human body? Have they reinvented themselves over the course of a few thousand years? Ancient bones might just throw up the answer.

Published by

Shweta Ramdas

Beginning life as a grad student studying human genetics.