A discovery of a parasite thought to originate in the Americas is challenging long-held ideas about ancient disease spread. Researchers have identified evidence of Cryptosporidium parvum in Roman-era chamber pots from Novae, a major military site in present-day northern Bulgaria.
The study, led by Elena Klenina and published in npj Heritage Science, examined mineralized waste deposits preserved inside Roman clay chamber pots. The vessels came from Novae and Marcianopolis, two important settlements in the Roman province of Moesia Inferior.
The findings offer a rare look at illness, hygiene, and daily life along the Lower Danube nearly 2,000 years ago.
Chamber pots reveal ancient infections
Researchers studied deposits left on the inner walls and bases of the chamber pots. These crusts formed from urine and feces. Because chamber pots were used by humans, the samples offer more direct evidence of human infection than soil from sewers or rubbish pits.
The team used microscopy, ancient DNA testing, and immunoassay methods. The tests found evidence of three parasites in samples from Novae: Taenia, Entamoeba histolytica, and Cryptosporidium parvum.
A single Taenia egg was seen under a microscope. This parasite, commonly known as tapeworm, usually spreads when people eat raw or undercooked infected meat. In Roman Novae, both pork and beef were common foods, so researchers could not determine which meat source caused the infection.
Tests also detected Entamoeba histolytica, a parasite that can cause amoebic dysentery. It spreads through contaminated food, water, or direct contact with infected people.
A parasite with a surprising history
The most striking result was the discovery of Cryptosporidium parvum. The parasite can infect humans, livestock, and wild animals. It often spreads through contaminated water.
Researchers noted that the parasite had long been linked to the Americas. Earlier evidence came from ancient coprolites in Mexico, dated to 600 to 800 CE. The new evidence from Roman Bulgaria suggests the parasite was also present in the Old World much earlier than expected.
The finding from Novae is especially important because Cryptosporidium is difficult to detect in ancient material. Its microscopic oocysts do not always survive well over time. Many older studies also did not use the type of immunoassay testing needed to identify it.
Water may have carried the disease
The researchers believe contaminated drinking water was the most likely source of infection at Novae. The villa where the chamber pots were found stood near the Roman military camp of Legio I Italica. Its water supply likely came from a system near the Danube.
Sewer channels in the area also led toward the river. Heavy rain or flooding may have allowed waste to enter the water supply. That could have exposed residents to parasites.
The villa was likely used by members of the military or administrative elite. These residents probably did not work directly with livestock. That makes contaminated water a stronger explanation than close contact with animals.
Still, food may also have played a role. Roman writers described the use of human waste as fertilizer. That practice could have contaminated crops. It could also have exposed animals to parasite eggs, later infecting people who ate their meat.
Marcianopolis showed no parasites
The study also tested a chamber pot from Marcianopolis, another Roman city in present-day Bulgaria. Researchers found no parasite evidence in that vessel.
They suggested several possible reasons. Marcianopolis may have had cleaner drinking water, supplied by nearby natural springs. The pot may also have contained mostly urine deposits, with little or no fecal material. Diet may have mattered as well, though researchers said more work is needed.
Study fills a gap in Balkan archaeology
The study is the first published parasite analysis from archaeological sites in Bulgaria. It also shows how chamber pots can help researchers study ancient health more accurately.
Unlike public latrines, chamber pots were often used by a smaller number of people. That makes them useful for studying disease in households, villas, or workplaces.
The findings suggest Roman sanitation systems did not always prevent infection, even among wealthier residents. They also show that parasites could move through water, food, and daily cleaning practices.
Researchers said the discovery opens new paths for studying disease in the eastern Balkans and Black Sea region. It also shows that ancient parasites may have had wider and more complex histories than previously believed.
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