Medieval Friars Were Riddled With Parasites, Say Archaeologists Medieval Friars Were Riddled With Parasites, Say Archaeologists

Medieval friars in Cambridge, England, were infested with almost twice as many parasites as were others in the city, according to a new study from university researchers reported in the International Journal of Paleopathology.

In the study, the archaeologists carefully compared soil samples from around the pelvises of adults buried at the Augustinian Friary between the 13th and 16th century with similar samples from townspeople interred nearby at All Saints by the Castle parish church between the 12th and 14th century.

Archeologists excavated the remains of friars buried at the former Augustinian friary in central Cambridge, United Kingdom.

To control for the possibility of later soil contamination from stool, the investigators also compared the amount of parasites found in soil samples from the pelvis with those from the skull and feet.

Remains of 19 monks and 25 locals were compared, and the researchers found that 11 friars (58%) — but only 8 (32%) of the townspeople — were infected by worms. Archaeologists were able to confirm remains as belonging to friars because of metal belt buckles found with the skeletons, part of that order’s standard attire.

Researchers passed soil samples through a series of microsieves to separate out particles of a size too large or too small to be parasite eggs. The mesh sieves had pores of 300 μm, 160 μm, and 20 μm. The 20 μm sieve would have collected the parasites, which were then suspended in glycerol and placed on slides. The researchers counted the eggs and identified their species at 400x magnification.

The researchers developed criteria to help confirm that the individual’s remains were truly infected with the parasites rather than the eggs being from contaminated soil. They said that this is the first time such criteria were used to rule out false positives, using egg counts at the feet and head as controls for those in the pelvis. But while ruling out false positives, the researchers acknowledged that those criteria probably lead to some false negatives.

Lead author Piers Mitchell, MD, PhD, University of Cambridge, told Medscape Medical News that this is “the first study in the world where we’ve looked at the monastic order and the general public at the same town so that you can see if the difference in lifestyle actually made a difference to your risk of getting parasite infection.” He added, “We thought that you might find similar results, or maybe even lower parasite infection in the Augustinians because they had proper toilets and things,” but they found that the opposite was true.

The team found roundworm and whipworm eggs, but no hookworm or tapeworm. Mitchell said hookworm eggs are much more fragile than the others, “and the pelvic soil of burials in a medieval town is not as great as dried coprolites in a cave.”

He had expected tapeworm eggs to be present because, being an Augustinian Friary, some days “they couldn’t eat meat, so they would eat fish. But being friary inside town, this particular monastery didn’t have its own fish ponds in the way that rural monasteries do…It looks like they were buying in sea fish and having that rather than having freshwater fish. In Europe, it’s the freshwater fish that has the fish tapeworm, and the sea fish doesn’t. So that’s probably why we didn’t detect it.”

The researchers acknowledged that they were surprised to discover that in Cambridge, the burial sites were dominated by parasites typically spread by poor sanitation. Because the friary had latrine blocks and handwashing facilities that ordinary workmen lacked, this was unexpected. Despite the worms, prior research suggests that those buried in medieval English monasteries lived longer than townspeople buried in parish cemeteries.

In addition to being a paleopathologist — an expert in diseases through the study of ancient remains — Mitchell runs the ancient parasites lab and teaches. And on top of that, he’s a practicing pediatric orthopedist.

Int J Paleopathol. Published online August 19, 2022. Full text

Mitchell reports no relevant financial relationships.

Judy Stone, MD, is an infectious disease specialist and author of Resilience: One Family’s Story of Hope and Triumph Over Evil and of Conducting Clinical Research , the essential guide to the topic. You can find her at or on Twitter @drjudystone.