A McMaster researcher has uncovered evidence of intestinal parasites in a 500-year-old latrine from Belgium, a finding that may induce queasiness in some, but is expected to provide important evidence of how infectious diseases once spread through travel and trade.  

 The findings, which have been published in the journal Parasitology, present some of the earliest evidence of schistosomiasis outside its endemic region of Africa.  

“Many of the parasites we see today have been around for centuries,” says Marissa Ledger, a postdoctoral fellow at McMaster’s Ancient DNA Centre who led the research.

“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.”  

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 kilometres from its endemic region.  

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 harbour 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 unique combination of this rich historical record with the archaeological and parasitological data improves our understanding of 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,” says Maxime Poulain, archaeologist at Ghent University.  

“It not only provides novel insight into 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.  

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.”