A Medieval City’s Sanitation Fix Backfired—and Unleashed a Vicious Cycle of Roundworm Infections

I have this distant memory of my high school medieval history teacher telling us that if we were magically transported into a medieval city, we’d faint from the overwhelming stench of its streets. Whether Mr. Armistead actually said this or the memory was influenced by the many historical movies and TV shows that depict the Middle Ages in this way, the iconic time period’s health and hygiene standards were certainly unenviable. This fact comes into particular focus thanks to a research project led by the NTNU University Museum in Trondheim, Norway: MedHeal600 (Medieval Urban Health: From private to public responsibility). Within the context of this project, archaeologist Elisabeth Forrestad Swensen’s PhD dissertation investigated how the city of Trondheim, then called Nidaros, handled waste, sewage, and drinking water in the Middle Ages and the early modern period, with implications for public health. Among other things, she found a viciously gross cycle of roundworm infection. A 12th-century latrine between two houses in Trondheim. © Riksantikvaren, Trondheim Back then, Nidaros’ inhabitants disposed of their bodily wastes and other types of waste in separate pits. Then during the High Middle Ages (1130–1350), a period during which populations—and their wastes—in Norway and the rest of Europe increased significantly, authorities in Trondheim ordered that fetid latrine waste be moved to pits outside of the city center. This move was likely because they believed that bad smells caused disease. “An analysis of the contents of these latrines reveals that nearly the entire population was infected with roundworms,” Swensen, who is museum director at the Armoury Museum in Trondheim, said in an NTNU statement. “This occurred because the latrine waste was incorporated into manure once it began being transported out of the city centre. Roundworms thrive especially well in manure.” What does manure have to do with human health, you might be wondering? If you really want to know, the infested manure was used in their agricultural lands, the same ones in which they grew their food. The parasite got into their food and then back into the city’s inhabitants. Gross. The archaeological record shows that Nidaros’ residents worked to solve their water and waste problems, according to the statement. But at least one of their solutions seems to have just made matters worse. “Measures were taken with clear, positive intentions; however, not all of them proved equally effective in practice,” Swensen said. “Although waste was often handled with care, certain changes may nonetheless have led to an increase in infectious diseases and parasites.” If Mr. Armistead is still teaching medieval history, he can now tell his students that if they were magically transported to Nidaros, they would faint and then promptly get roundworm.