Scientists are reconsidering an ancient disease found in prehistoric Vietnam and challenging some of the basic assumptions archaeologists use to study past infections.
The international research team behind the study investigated the skeletal remains of children who inherited a treponema disease from their mothers through congenital transmission, in cases previously identified as venereal disease.
Archaeological sites in both northern and southern Vietnam yielded cases dating between 3,200 and 4,000 years old, which were analyzed for a new paper published in the International Journal of Osteoarchaeology, providing new insights as climate change continues to reawaken ancient diseases.
Disease in Ancient Remains
The new research comes from a much larger study of infectious diseases across Vietnam, spanning sites from north to south, and including both adults and children.
“While the overall sample covered all age groups, the clearest signs of infection passed from mother to baby showed up in infants and younger individuals,” Lead author Dr. Melandri Vlok told The Debrief. “That doesn’t mean these infections can’t be seen in adults—they can, and some features, like defects in tooth enamel formed in childhood, remain visible for life, but we didn’t find any in the adults that could be tied to congenital transmission.”
Among the remains, the researchers identified congenital treponematosis indicators in the teeth and bones of three children. This group of diseases includes syphilis, yaws, and endemic syphilis. Looking at the pattern of disease in the area’s wider population reveals non-venereal treponema disease, like yaws, instead of venereal syphilis as the most likely culprit. A tropical disease with over 150,000 sufferers, Yaws leads to permanent disability.
Rethinking Ancient Disease Spread
Notably, two of the children came from the Man Bac sites, already associated with high rates of treponema diseases. Researchers had already suspected that these sites were likely victims of a non-venereal outbreak spread through skin contact due to the many cases seen in children and adolescents.
The team says their work represents a shake-up in thinking on the controversial origins of syphilis. Past researchers based their assertion that syphilis outside of the Americas predated the voyages of Christopher Columbus due to evidence of congenital cases found in skeletons.
This work argues that evidence of congenital cases is not reliable evidence of venereal syphilis over other types of treponema diseases.
“For years, scientists have argued over where syphilis came from: whether it existed around the world long before Columbus, or whether it was brought back to Europe after his voyages to the Americas,” Dr. Vlok explained. “New ancient DNA discoveries have added excitement to the debate, with researchers finding evidence of related bacteria in very old remains from the Americas as early as 5500 years ago. But here’s the key point: these aren’t actually syphilis, just close relatives in the same disease family.”
“Because modern medicine links mother-to-baby transmission strongly with syphilis, archaeologists have often taken signs of this in ancient children as proof of syphilis in the past,” Dr. Vlok added. “For those who support origins in the Americas, they have been combining the aDNA evidence of non-syphilitic strains with the mother-to-baby transmission evidence from traditional skeletal studies as definitive proof.”
Connecting Ancient Disease to the Modern World
“At one of the sites called Man Bac in northern Vietnam, dated to between 3500-4000 years ago, more than 10% of the people buried had evidence of treponemal disease written in their bones,” Dr. Vlok said. “Less than approximately 5% of people affected with treponemal disease will develop skeletal disease, so the 10% reported at the site can be expected to be the tip of the iceberg.”
“The impacts if they do affect the bones and joints are highly disfiguring and disabling, so the burden on the community would have been extensive,” Dr. Vlok added.
The work done by Dr. Vlok and her team isn’t merely an archaeological curiosity. A changing climate is leading to a resurgence in Yaws cases, and earning how these diseases have ravaged human populations in the past may be essential knowledge in halting their return.
“Treponemal diseases have a far more complex history than we once thought,” Dr. Vlok concluded. “Understanding that complexity is essential if we want to reconstruct how infectious diseases shaped human history. Especially as treponemal disease like yaws is re-emerging due to the climate crisis.”
The paper, “Dental Stigmata and Skeletal Lesions of Congenital Treponematosis in Early Agricultural Vietnam (4000–3500 bp),” appeared in The International Journal of Osteoarchaeology on February 28, 2026.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.