Mar 26, 2017 I Brett Tingley

First Depiction of Human Parasite Found in Medieval Painting

One of the creepiest and most nauseating parasitic infections is dracunculiasis, also known as Guinea worm disease (GWD). Jimmy Carter’s least favorite parasite is spread by certain species of water fleas which eat the larvae of the Guinea worm. When humans drink water containing the microscopic water fleas, the Guinea worm larvae burst from the fleas and enter the human body. Within a year, the worm can find its way into the tissues of the human body and form massive, painful weeping lesions. These lesions burst and mature, 3-foot-long (1 meter) Guinea worms exit the body to lay eggs and continue the vicious cycle. Gross.

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A Guinea worm making its way out of an affected individual's leg.

While Guinea worm disease has been well-known throughout many parts of the world for centuries, historical depictions of the worm are scarce for what are likely ethnocentric reasons. The worm primarily strikes individuals in African countries, so documented histories in the West are rare. However, art historians in Italy have recently uncovered what they believe is the earliest-known depiction of the Guinea worm in a medieval painting of a popular Crusades-era saint on display at the Pinacoteca di Brera (Painting Gallery), located in Milan.

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Detail of the painting showing a totally gross Guinea worm infection.

The painting depicts Saint Roch, a patron of dogs, falsely accused people, and bachelors, and who is typically invoked as a defense against plagues. Depictions of St. Roch usually include a bulbous boil-like sore on his thigh thought to represent various plagues.

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Uh...yep. That's a bulbous leg boil all right.

The particular painting in this study, however, depicts a long, worm-like object bursting forth from an openly abscessed leg sore. Previous analyses guessed that the object weeping forth was a long, disgusting strand of pus. Blech. However, given that Guinea worms typically exit through a sore on one’s leg exactly like in the picture, researchers now believe that this painting of Saint Roch instead depicts the pilgrim suffering from Guinea worm disease:

Art historians have always 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, from the Pharaohs’ Egypt to Mesopotamia and ancient Greece, as well documented by several sources like the Old Testament and the Greek writer Agatharchides.

This painting complicates our historical understanding of Guinea worm disease and its distribution. The fact that a 15th-century Italian painting depicts the parasite means that pilgrims returning from the Crusades might have brought the disease back with them to Europe, much to the surprise of paleopathologists. Today, thanks to education, water sanitation efforts, and medical care, only a few dozen cases of Guinea worm disease are reported worldwide each year. The disease might soon be the first parasitic infection to be completely eradicated. Thanks, Jimmy Carter.

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No seriously, thanks Jimmy Carter. His Carter Center has led the international campaign to eradicate Guinea worm disease for the last three decades.

Brett Tingley

Brett Tingley is a writer and musician living in the ancient Appalachian mountains.

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