historyWellcome Collectionmedieval · Europe

Parasites and pests from the medieval to the modern

the gist

Medieval people suffered from intestinal worms and lice, and excavations of latrines show parasites were common. Richard III had roundworm when he died at Bosworth, and Ferdinand of Naples had head and pubic lice, so even the very rich were affected. People were just as bothered as we are. Doctors believed worms arose by spontaneous generation from 'corrupt matter' in the gut, produced by an excess of phlegm from overeating or the wrong foods, and recommended treatments aimed at diet and purging.

how it works

Medieval doctors followed the Greek theory of four humours. Excess phlegm was thought to produce worms, so treatments tried to rebalance the humours through diet, purging and herbal remedies.

so what

Archaeology and records show that disgust at parasites is old. The explanation was wrong, but the medieval belief that diet and cleanliness mattered reasoned from observation.

fun fact

Parasite eggs are preserved in latrine soil, which is how archaeologists identify them.

Wellcome Collection · CC BY 4.0

Illustrative photo · Marco Vinci, CC BY-SA 3.0, via Wikimedia Commons