Public baths, latrines with washing facilities, sewer systems, fountains and clean drinking water from aqueducts did not protect the ancient Romans from parasites, finds new research.

Published in the journal Parasitology, the study used archaeological evidence from cesspits, sewer drains, rubbish pits, burials and other sites to assess the impact of Romanization across Europe, the Middle East and North Africa.

Piers Mitchell from the Department of Archaeology and Anthropology of the University of Cambridge, UK, reviewed and compared the evidence for parasites before, during and after the Romans.

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Surprisingly, analysis of ancient latrines, human burials and coprolites, or fossilized feces, showed that intestinal parasites did not decrease as expected in Roman times compared with the preceding Iron Age. Actually, they gradually increased.

“The impressive sanitation technologies introduced by the Romans did not seem to have delivered the health benefits that we would expect,” Mitchell told Discovery News.

He found that the most widely spread intestinal parasites in the Roman Empire were whipworm (Trichuris trichiura) and roundworm (Ascaris lumbricoides) which are transmitted by the contamination of food with feces.

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“It could have been spread by the use of unwashed hands to prepare food or by the use of human feces as crop fertilizer,” Mitchell wrote.

Also widespread was Entamoeba histolytica, a protozoan that causes dysentery, with bloody diarrhea, abdominal pain and fevers. It is contracted by drinking water contaminated by human feces.

Ectoparasites such as lice and fleas were as common among Romans as in Viking and medieval populations, where bathing was not widely practiced.

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The finding is surprising since the Romans are known for their regular bathing and for building latrines provided with flushing systems. They took care of their personal hygiene with a sponge on a stick and hand washing.

“I would not say that these technologies were useless. Public latrines would be been convenient in town while public baths would have made people cleaner and smell better,” Mitchell said.

“It is just that they do not have appeared to improve health in the way we might expect and we must ask ourselves why,” he added.

One possible explanation might lie in regulations which ensured human waste was cleared from the streets and taken out of towns to the countryside.

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“This human and animal feces was often used to fertilize crops, thus leading to reinfection of the population with intestinal parasites when they ate this food,” Mitchell said.

Indeed, unless the feces are composted for many months before being added to the fields, they can spread parasite eggs to the plants grown.

Moreover, not all Roman baths were clean. Water was often changed intermittently, and a scum would build on the surface from human dirt and cosmetics.

The study also found fish tapeworm eggs surprisingly widespread in the Roman empire, in contrast to the evidence from the Bronze and Iron Age.

The Roman love for the fermented fish sauce known as garum may provide an explanation.

Traded across the empire, garum was made from pieces of fish, herbs, salt and flavorings. The sauce was not cooked, but allowed to ferment in the sun.

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“Fish tapeworm eggs could have been transported large distances across the empire in the garum sauce and then consumed,” Mitchell said.

Roman doctors such as Galen (130-210 A.D.), a physician to the Roman emperors Marcus Aurelius, Commodus and Septimus Severus, were well aware of intestinal worms.

Galen believed the parasites were formed spontaneously from putrefied matter under the effect of heat.

The treatment consisted in dietary modification, bloodletting and medicines that were believed to have a cooling and drying effect.

As for ectoparasites such as lice, the treatment consisted of special combs which were used to strip the parasite from hair.

“Delousing may have been a daily routine for many people living across the Roman Empire,” Mitchell said.