Microscopic Analysis of Roman Poop Proves Their Engineering Couldn’t Save Them From Parasites

Excavations reveal the microscopic enemies plaguing Roman soldiers at Hadrian's Wall.

History loves to romanticize the Romans. We see them as the “good” empire — organized, clean, and civilized. They brought us aqueducts, heated floors, and sanitation. But if you zoom in on their nasty business, a different reality squirms into view. Quite literally.

Researchers recently did exactly that. They zoomed in on Roman poop and found a trio of intestinal miseries: roundworm, whipworm, and Giardia duodenalis.

At the Roman fort of Vindolanda, just south of Hadrian’s Wall, the Romans fought the Pict tribes. But archaeologists uncovered evidence of a different, microscopic battle. For the soldiers stationed on this wet, windy frontier, these infections meant chronic discomfort, nutritional deficiencies, and severe diarrhea. The Romans brought their architecture and their armies to Britain, but they also brought their parasites.

The Myth of Cleanliness

Vindolanda offers a remarkable, well-preserved glimpse of Roman life. The Romans built Hadrian’s Wall in the early 2nd century AD to defend Britannia from northern tribes, and the site remained active until the 4th century.

The site is famous for its wooden writing tablets and leather goods, but excavations of a 3rd-century bathhouse drain revealed an unpleasant biological reality. Researchers collected 58 sediment samples from a drain connected to the bathhouse latrine. The results were telling: 28% of the samples from the primary fill contained helminth (worm) eggs.

Finding Ascaris and Trichuris isn’t entirely surprising; they are soil-transmitted worms that have plagued humans for millennia. However, the discovery of Giardia is a different story.

This protozoan causes dysentery and is notoriously difficult to detect in archaeological samples because, unlike worms, it doesn’t leave behind a durable eggshell. To find it, the team used a technique called ELISA (enzyme-linked immunosorbent assay) to hunt for specific proteins the parasite leaves behind.

High Tech, Low Health

Taken together, this trio of parasites shares a common method of transmission: the fecal-oral route.

This reveals a major flaw in the efficiency of Roman engineering. The Vindolanda bathhouse featured water channeled from a spring and a complex drainage system to remove waste. Yet, the presence of these specific parasites proves the system failed to protect the soldiers’ health.

The pathogens were likely cycling through the population via contaminated food and drinking water. The technology was impressive, but the sanitation was ineffective.

“Despite the fact that Vindolanda had communal latrines and a sewer system, this still did not protect the soldiers from infecting each other with these parasites,” said Dr Patrik Flammer, who analysed samples at the University of Oxford.

Unclogging the History

The Romans likely knew they had a problem. In large urban centers like London and York, archaeologists often find a diverse “zoo” of parasites, including tapeworms and flukes. Surprisingly, Vindolanda actually had fewer parasites than many other sites.

“The three types of parasites we found could have led to malnutrition and cause diarrhoea in some of the Roman soldiers,” said Dr Marissa Ledger, who led the Cambridge component of the study as part of her PhD at the University of Cambridge’s Department of Archaeology.

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“While the Romans were aware of intestinal worms, there was little their doctors could do to clear infection by these parasites or help those experiencing diarrhoea, meaning symptoms could persist and worsen. These chronic infections likely weakened soldiers, reducing fitness for duty. Helminths alone can cause nausea, cramping and diarrhoea.”

The historical record backs this up. One famous tablet from Vindolanda mentions a report on the “First Cohort of Tungrians,” noting that ten men were unfit for duty due to lippitudo, or conjunctivitis.

Conjunctivitis wasn’t the only problem. Roman hygiene was remarkable for its time, but it was far from perfect. They built walls to keep the barbarians out, but within the fort, one parasitic threat was already inside the gates.

Journal Reference: Marissa L. Ledger et al, Parasite infections at the Roman Fort of Vindolanda by Hadrian’s Wall, UK, Parasitology (2025). DOI: 10.1017/s0031182025101327