How old are bacterial pathogens?

Abstract

Only few molecular studies have addressed the age of bacterial pathogens that infected humans before the beginnings of medical bacteriology, but these have provided dramatic insights. The global genetic diversity of Helicobacter pylori , which infects human stomachs, parallels that of its human host. The time to the most recent common ancestor (tMRCA) of these bacteria approximates that of anatomically modern humans, i.e. at least 100 000 years, after calibrating the evolutionary divergence within H. pylori against major ancient human migrations. Similarly, genomic reconstructions of Mycobacterium tuberculosis , the cause of tuberculosis, from ancient skeletons in South America and mummies in Hungary support estimates of less than 6000 years for the tMRCA of M. tuberculosis . Finally, modern global patterns of genetic diversity and ancient DNA studies indicate that during the last 5000 years plague caused by Yersinia pestis has spread globally on multiple occasions from China and Central Asia. Such tMRCA estimates provide only lower bounds on the ages of bacterial pathogens, and additional studies are needed for realistic upper bounds on how long humans and animals have suffered from bacterial diseases.

Epidemiology of Helicobacter pylori infection

“…Helicobacter pylori was dispersed globally with its human host resulting in distinct phylogeographic patterns that can be used to reconstruct both recent and ancient human migrations. Mark Achtman in a recent paper reviewed the 20 last year researches on this exciting topic . A striking number of parallels were made between the genetic patterns and sources of native human populations and their associations with population of H. pylori .…”

“…Mark Achtman in a recent paper reviewed the 20 last year researches on this exciting topic. 1 A striking number of parallels were made between the genetic patterns and sources of native human populations and their associations with population of H. pylori. But not all geographical patterns are concordant between H. pylori and humans.…”

Ancient oncogenesis, infection and human evolution

“…Some studies have nevertheless addressed the age of bacterial pathogens that infected ancient humans, and many of these have provided significant insights into pathogen evolution. Comparative genomics can reconstruct short‐term evolutionary histories of pathogen clades whose diversity converges towards a most recent common ancestor (MRCA) that existed decades, centuries or even millennia ago (Achtman, ; Der Sarkissian et al., ). For example, following calibration of the evolutionary divergence within H. pylori against ancient human migrations, the MRCA of H. pylori approximates that of anatomically modern humans.…”

Positive Diagnosis of Ancient Leprosy and Tuberculosis Using Ancient DNA and Lipid Biomarkers

“…The dogmatic view continues, that anything short of a full genome is unacceptable. This sustained subjective denial of the value of aDNA amplification [109] also totally and conveniently ignores the solid body of lipid biomarker evidence for landmark cases, such as the~9ka Atlit-Yam woman and child ( Figure 3) [28] and the~17 ka bison ( Figure 5) [29]. Indeed, deliberately ignoring ancient lipid data is tacit evidence of the value of these biomarkers that are difficult to dismiss on contamination grounds as no amplification is involved.…”

“…The supposed~6 ka TB MCRA limit has been subjectively relaxed in a recent review, but still the authenticity of any older cases remain denied [109]. The dogmatic view continues, that anything short of a full genome is unacceptable.…”