[Syphilis and human treponemes: a long evolutionary history revealed by paleogenomics]

Recent discoveries in paleogenomics have revolutionized our understanding of syphilis and other human treponematoses. Far from being a pathogen that suddenly appeared in Europe in the late Middle Ages, we now know that Treponema pallidum has been circulated among human populations for millennia. Ancient genomes recovered from pre-Columbian contexts in the Americas show that major treponemal lineages had already diversified well before the modern era, often in the absence of recognizable skeletal lesions. Genomic analyses further indicate that treponemal diversity is not the result of extensive genetic acquisition, but rather of small-scale modulation of a highly conserved genome, notably via antigenic variation involving the tpr gene family. Combined with data on endemic treponematoses, congenital syphilis, and historical pathology collections, these findings support a model in which syphilis, yaws, and bejel represent context-dependent expressions of an ancient treponemal continuum, with implications for diagnosis, epidemiology, and vaccine design.