Medieval waste management policies in Trondheim led to roundworm infections

Archaeologists and researchers at the NTNU University Museum discovered that medieval public health initiatives in Trondheim, Norway, unintentionally facilitated the spread of parasites.

By examining skeletons from two distinct cemeteries, the team identified how social inequality influenced health. Residents in the city's periphery, mostly craft workers, suffered higher child mortality and poorer health than the social elite living near the central church, who enjoyed a more diverse diet including seafood.

The research project MedHeal600 examined how public authorities moved health and waste management from private concerns to communal responsibilities between the years 1000 to 1600. During the High Middle Ages, authorities attempted to improve hygiene by moving foul latrine waste to pits outside the city center. They believed that unpleasant smells, or miasmas, caused diseases. However, this move backfired because the waste was mixed with manure, which allowed roundworms to thrive.

These parasites then entered the food supply when the manure was spread on agricultural land, creating a cycle of infection for the city's inhabitants. Environmental and economic shifts further altered the city's sanitation practices. A shortage of wood chips, caused by a 1257 volcanic eruption and a decline in house construction, caused the stench of waste pits inside the city to worsen.

In response, authorities eventually moved all organic waste outside the city limits, which reduced the risk of certain infectious diseases. These findings contribute to a broader understanding of how the population of Norway declined from 500,000 in 1340 to 200,000 by the early 16th century due to repeated plague outbreaks.