Ancient Skeletal Evidence Shifts Understanding of Treponemal Diseases

A recent study spearheaded by researchers from Charles Sturt University and their international counterparts is turning the conventional understanding of ancient diseases on its head. Evidence derived from the skeletal remains of children in prehistoric Vietnam suggests that congenital transmission of treponemal diseases may have occurred thousands of years ago, not just limited to venereal syphilis, as previously thought.

Examining Ancient Remains

The research team, led by Dr. Melandri Vlok, a Lecturer in Anatomy and Physiology, analyzed skeletal remains from various archaeological sites around northern and southern Vietnam, dating back approximately 4,000 to 3,200 years. Within this analysis, clear signs of congenital treponematosis were identified in three children. Treponematosis is a term encompassing diseases such as syphilis, yaws, and endemic syphilis.

Patterns Pointing Away from Venereal Syphilis

The findings challenge the long-held assumption that congenital infection in ancient skeletal remains is strong evidence of venereal syphilis. The patterns revealed in the skeletal data suggest a possible nonvenereal treponemal disease, such as yaws, being the culprit for the children’s ailments. Yaws, which impacts many tropical regions, can lead to severe long-term disabilities.

Dr. Vlok emphasized this shift: "For decades, congenital infection in archaeological remains has often been taken as strong evidence of venereal syphilis. Our research shows that this assumption may not always hold true. Other treponemal diseases may also have been transmitted from mother to child."

Investigating Man Bac

The study focused particularly on two children recovered from the Man Bac site in northern Vietnam, an area noted for previously high rates of treponemal diseases. The infection rates among children and adolescents there further align with the patterns typical of more benign treponemal diseases spread by skin contact rather than sexual behavior, suggesting a significant departure from venereal transmission.

"The epidemiology of the site strongly points toward a non-venereal form of treponemal disease," Dr. Vlok noted, adding that the finding of congenital transmission amid such epidemiology is particularly surprising.

Rethinking Syphilis Origins

The implications of this research extend to one of the longstanding debates in medical history: the origins of syphilis. Historically, the evidence of congenital infection has served as a linchpin in discussions about whether syphilis existed in Europe prior to Columbus's voyages to the Americas. The current study suggests that merely detecting congenital cases may not be a reliable marker for venereal syphilis, as other treponemal infections could produce similar evidence.

Dr. Vlok pointed out the potential misinterpretations: "Some cases previously labeled as congenital syphilis may represent entirely different diseases." So far, there’s been no confirmed biological or genetic evidence of pre-Columbian venereal syphilis outside the Americas.

Challenges in Ancient DNA Research

The study also sheds light on the challenges of working with ancient infectious diseases, particularly in tropical regions like Southeast Asia, where ancient DNA is notoriously difficult to preserve. This fragility complicates efforts to determine the specific pathogens involved in historical populations and is compounded by evolving ethical standards regarding the destructive sampling of human remains.

Co-lead author Ms. Minh Tran, a PhD student from the University of the Philippines, shared insights on the future of research: "In tropical environments, recovering ancient DNA is incredibly difficult, and destructive sampling raises important ethical questions. Future research must move in new directions, working genuinely with communities connected to these remains."

New Directions for Treponemal Research

Ultimately, the researchers call for a shift in focus from merely identifying the origins of syphilis to understanding the broader evolution of treponemal diseases alongside human societies and changing environments. Dr. Vlok concluded, "Treponemal diseases have a far more complex history than we once thought. Understanding that complexity is essential to reconstruct how infectious diseases have shaped human history—especially as diseases like yaws are re-emerging due to the climate crisis."

Source materials provided by Charles Sturt University. Content may be edited for style and length.

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