A parasite once thought to be a New World Native
Modern analytical tools have given researchers something close to a time machine. From contemporary laboratories, scientists can reconstruct the daily lives, hygiene habits, and health struggles of people who lived hundreds of years ago. In one recent example, a team of Polish researchers turned their focus to the Roman province of Moesia Inferior, analyzing the dried remnants of human waste preserved in Roman latrines dating from the 2nd to 4th centuries CE.
As explained here, what they found inside the intestinal histories of those long-dead inhabitants was striking: parasites, including tapeworms and protozoa—organisms notorious for causing abdominal pain, chronic diarrhea, and persistent fatigue.
The most unexpected finding was the presence of Cryptosporidium, a protozoan parasite, in the majority of samples. Previously, researchers believed this pathogen originated in Central America. The study, published in npj Science Heritage, now stands as the earliest confirmed evidence of Cryptosporidium in the Mediterranean world.
Scientific interest in paleoparasitology—the study of parasites recovered from archaeological sites—gained momentum in the early 2000s, spurred by breakthroughs in detection technology that made identifying microscopic traces far more feasible.
The researchers began collecting samples in 2022 from two sites near modern-day Svishtov in Bulgaria: Novae, a major Roman legionary fortress, and Marcianopolis, an important stronghold along the lower Danube frontier. After nearly two millennia, the urine and feces deposited in Roman chamber pots had transformed into hard, mineralized crusts on ceramic surfaces. The team used scalpels to carefully scrape material from two distinct zones: the inner walls, where liquid waste had splashed and dried, and the vessel bottoms, where solid matter and minerals had compacted over time.
These samples were rehydrated, filtered through ultra-fine sieves to isolate parasite remnants, and then examined under microscopes at 400× magnification to detect eggs and other biological traces. Because several parasites are nearly indistinguishable under a microscope, the team also employed ancient DNA (aDNA) analysis for more precise identification. They further used ELISA—a technique in which antibodies bind selectively to specific parasite proteins, triggering a visible color change in the sample if the target is present. This method proved particularly valuable for detecting Cryptosporidium, whose delicate remains tend to break down over centuries.
In addition to the Cryptosporidium discovery, the analysis identified Entamoeba histolytica — the parasite responsible for amoebic dysentery — along with tapeworm eggs, suggesting the consumption of raw or undercooked beef or pork.
The two cities told markedly different parasitic stories. Samples from Novae were heavily contaminated, likely reflecting polluted water drawn from the Danube or compromised aqueducts. By contrast, samples from a workshop in Marcianopolis showed no parasite activity at all—possibly because its inhabitants had access to cleaner water from nearby natural springs, or simply maintained a better diet.
Together, these findings offer a rare window into how infectious diseases spread in the ancient world—and a clearer understanding of the past remains essential to tracing how such illnesses have evolved to the present day.