The painting of St. Roch in the picture gallery of Bari (15th century): an ancient representation of dracunculiasis?

the picture gallery of Bari (Apulia, Italy) houses a painting of Saint Roch - French pilgrim and thaumaturgist of the mid 14th century - depicted by an anonymous author between the end of the 15th and the beginning of the 16th century. In our altarpiece the figure of the Saint is represented traditionally as a bearded man dressed with the typical clothes of the pilgrim, holding a sharp stick with his right hand and indicating with the left hand a swelling on the thigh, made visible by the rolled sock. The altarpiece of Bari, in addition to the canonic representation, adds a new realistic detail that is a white thin filament that comes out of the lesion and almost reaches the knee. Art historians have identified this element as a long drop of pus emerging outside of the infected wound. We believe instead that the painter portrayed an ancient case of dracunculiasis, an infectious disease caused by a nematode worm, the Dracunculus medinensis, well known in antiquity. D. medinensis is a parasite that, at the end of its maturative and reproductive cycle, reaches several centimeters in length and causes the formation of a blister on the skin's surface, generally on the lower extremities, from which slowly emerges over the course of several days or weeks. Dracunculiasis was a disease localized especially in the Sub-Saharan Africa, India and even in the Middle East, whereas it is not documented in Italy. The author of the painting however worked definitely in Bari, a very important port for the travels to the East, especially Syria and Palestine. It is possible therefore that the painter noticed the parasite in the wounds of some traveler arrived from the sea and would like to portray it in his masterpiece as a note of extreme realism. The features depicted in the painting represent therefore, in our opinion, the unique case of ancient dracunculiasis in the history of European art.