Ancient Vietnamese Remains Suggest Yaws, Not Syphilis, Can Pass From Mother to Child

What the Vietnamese Skeletons Reveal

An international team led by Charles Sturt University researcher Dr Melandri Vlok examined 309 individuals from 16 archaeological sites in Vietnam, spanning roughly 10,000 to 1,000 years before present. Three young children, whose remains date back at least 3,500 years, carried dental abnormalities and skeletal lesions consistent with congenital treponematosis, a family of infections caused by Treponema pallidum bacteria.

Congenital disease has historically been read as a marker of venereal syphilis, but the study, published in the International Journal of Osteoarchaeology, suggests the broader infection pattern at the Man Bac site points elsewhere. Most cases appeared in children and adolescents, a distribution more typical of a nonvenereal infection such as yaws that spreads through skin contact in tropical conditions.

The implication is significant for the history of disease: if nonvenereal treponemal infections can pass from mother to child, researchers can no longer assume congenital skeletal signs equal syphilis. That assumption has been central to arguments about whether syphilis existed in the Americas or Europe before the voyages of Christopher Columbus.

No confirmed pre-Columbian genetic evidence of venereal syphilis exists inside or outside the Americas, and tropical ancient DNA is rarely well-preserved. The authors, including University of the Philippines PhD student Minh Tran, also emphasise that future biomolecular work should occur only with community partnership and preservation safeguards.

Why the Man Bac Evidence Weakens a Long-Held Test

What the Man Bac Age Pattern Suggests

The concentration of infections among children and adolescents at Man Bac is key. Venereal syphilis is typically associated with adult sexual transmission, while yaws and endemic syphilis spread through skin contact and often appear earlier in life. Because the site's epidemiology points toward a nonvenereal disease — yet congenital cases still appear — the study separates congenital transmission from a syphilis-only interpretation.

Why This Matters for the Syphilis Origins Debate

Researchers have frequently used congenital skeletal lesions as a diagnostic shortcut for venereal syphilis in debates about pre-Columbian disease. This study indicates that shortcut can produce false positives for syphilis when the remains may instead reflect yaws or another related infection. It does not resolve where syphilis originated; instead, it lowers the evidential weight that skeletal congenital signs alone can bear.

The Limits of Ancient DNA in the Tropics

The research also illustrates why genetic confirmation is difficult. Ancient DNA degrades quickly in hot, humid environments such as Southeast Asia, and destructive sampling raises ethical concerns. As a result, the authors argue the next phase of work should focus less on a single origin story and more on how different treponemal diseases evolved alongside human communities.