Parasites Found in 500-Year-Old Toilet Reveal Shocking Evidence of Global Medieval Disease Networks
Evidence of a 500-year-old African parasite in Bruges reveals how medieval trade networks spread infectious diseases. Researchers link the finding to Spanish merchants and global trade, offering insights into historical health and migration.
A McMaster researcher has discovered evidence of intestinal parasites in a 500-year-old latrine in Bruges, Belgium. While the discovery might seem unsettling, it offers valuable insights into how infectious diseases spread through travel and trade in the past.
The research, published in the journal Parasitology, includes some of the earliest evidence of schistosomiasis found outside its endemic region in Africa.
“Many of the parasites we see today have been around for centuries. One of our goals in infectious disease studies is to understand where in the world people had these parasites in the past and how their epidemiology has changed through time,” says Marissa Ledger, a post-doctoral fellow at McMaster’s Ancient DNA Centre, who led the research.
Schistosomiasis is caused by Schistosoma mansoni, a water-borne parasitic flatworm that can burrow into the skin, move through the bloodstream, and establish itself in the intestines. There it reproduces and releases eggs, which are passed through human waste. Ledger discovered a preserved egg in the contents of a 15th-century latrine in present-day Belgium, thousands of kilometers away from its endemic region.
Archaeological Context of the Latrine
The latrine had been uncovered in an excavation in 1996, but its artifacts and organic remains were only recently examined as part of a larger research project at Ghent University focused on the many foreign communities living and trading in medieval Bruges and its former harbor towns.
Researchers say the latrine came from a house known as the Spanish nation house, the administrative seat and meeting place of the Castilian merchant community. The parasite in question is likely associated with one of these Spanish traders who facilitated the import of African commodities like gold dust, ivory, and various spices. There’s also evidence they were involved in the early Atlantic slave trade.
The Spanish nation house, where the latrine was excavated, with adjacent warehouses on the right and the buildings formerly belonging to the Spanish merchant Francisco de la Torre on the left. Copper engraving colored with watercolor from Sanderus’s Flandria illustrata. Credit: 1641, Ghent University LibraryThe combination of this rich historical record with the archaeological and parasitological data is quite unique and helps us better understand human migration and disease transmission in the past and underscores the historical significance of this Belgian-Canadian collaboration.
“Our findings speak to the complexity of medieval urban life and how interconnected this world was centuries ago. It not only provides novel insight into the daily life of people in medieval Bruges but also shows how the city, known as an international hub for people, goods and ideas, inevitably also facilitated the spread of diseases through its strong maritime trade networks,” says Maxime Poulain, an archaeologist at Ghent University.
Broader Implications of the Findings
It also demonstrates the importance of analyzing organic remains from these types of archaeological finding, as it can provide information on the health, hygiene and mobility of populations.
Ledger plans to analyze the genetics of the parasite to understand how its makeup compares to that of its modern counterparts.
“Understanding these parasites over a broader time frame provides more information on how they are impacted by factors like migration. Even in the past as people were migrating over these long distances, they were still very effectively moving infectious diseases across long distances. That’s incredibly useful to know.”
