Challenging definitions and diagnostic approaches for ancient rare diseases: The case of poliomyelitis

Objective: This paper aims to contribute to the definition of ancient rare diseases in skeletons displaying pathologies associated with paralysis. It uses a new suite of methods, which can be applied to challenging cases of possible paralysis in archaeologically-derived human skeletal material, specifically applied to the identification of poliomyelitis.

Materials: An adult male skeleton from Roman Halbturn, Austria.

Methods: Morphological and entheseal change analyses, CT scans, X-rays, cross-section morphology, and histology, alongside modern clinical, as well as historic, literature were used to discuss paralyses.

Results: The results suggest a diagnosis of poliomyelitis; now considered a rare disease, but perhaps ubiquitous in antiquity, thus complicating the definition of 'rare disease'.

Conclusions: The integrated methodological procedures employed for this case constitutes a replicable and thorough approach to diagnosis, and explores the nature of ancient rare diseases. Due to the socio-environmental aspects of poliomyelitis transmission, it is likely that polio was likely not rare in the past. Therefore, the definition of 'rare diseases in the past' must include rarely occurring rarely diagnosed diseases due to biases and challenges within the archaeological and environmental record.

Significance: The developed suite of methods has not been applied to establish a diagnosis of polio in the past.

Limitations: The individual considered in this study is fairly well-preserved; thus, this set of analyses may not be applicable to all remains where preservation is poor or highly fragmentary, and the discussion of rare diseases requires relatively secure diagnoses and context.

Suggestions for further research: Large collections and series of skeletal human remains are recommended to develop definitive conclusions.