A 2,000-year-old specimen with intraerythrocytic Bartonella quintana

Photogrammetry and cascading microscopy investigations of dental pulp specimens collected from 2,000-year-old individuals buried in a Roman necropolis in Besancon, France, revealed unprecedented preserved tissular and cellular morphology. Photogrammetry yielded 3-D images of the smallest archaeological human remain ever recovered. Optical microscopy examinations after standard hematoxylin-phloxine-saffron staining and anti-glycophorin A immunohistochemistry exposed dental pulp cells, in addition erythrocytes were visualized by electron microscopy, which indicated that the ancient dental pulp trapped a blood drop. Fluorescence in situ hybridization applied on red blood cells revealed the louse-borne pathogen Bartonella quintana, a finding confirmed by polymerase chain reaction assays. Through paleohistology and paleocytology, we demonstrate that ancient dental pulp preserved intact blood cells at the time of the individuals death, offering an unprecedented opportunity to engage in direct and indirect tests to diagnose pathogens in ancient buried individuals.