Ancient calculus egg

Sir, optical microscope examination of dental calculus deposits (DCD) has recently proven its importance for both ancient and recent populations in order to describe the pathological background of individuals.^1,2,3

In the DCD of an individual from the ninth century AD, discovered buried in a silo (Villiers-le-Bel S1441, close to Paris, France), was identified a Schistosoma mansoni egg of 100 mm maximal length, with its characteristic lateral spine (HES coloration, magnification × 200). Slight deformation is due to short-term decalcification by the acetic acid and rehydration process.

As for the previous diagnosis of comparable eggs from a French fifteenth-sixteenth century AD latrine (Montbéliard),⁴ and because the parasite has an African origin,⁵ our main hypothesis is of an imported case (slave? traveller? merchant?).

This case – the oldest evidence of the parasite in Europe – highlights the interest of such samples and microscope technique for retrospective diagnosis. Dental calculus represents a very informative sample for the reconstruction, not only of commensal microbes, but also the pathological background of individuals, including parasitological infections.