The study suggests the use of multi-seat public latrines - shown on the left - may have contributed to the increase in parasites like the whipworm, an egg of which is shown on the right, found in a Roman excavation in Turkey.
Image credits: Left: Craig Taylor. Right: Piers Mitchell
The impression is that this made people cleaner and healthier. But new archeological evidence suggests that, despite the apparent improvements, the new sanitation systems may have led to an increase rather than a decrease in diseases like intestinal parasites.
This was the conclusion Dr. Piers Mitchell, from the Department of Archaeology and Anthropology at the University of Cambridge in the UK, came to after carrying out a study published in the journal Parasitology.
Dr. Mitchell, whose research interests include the interaction between humans and parasites throughout evolution, says:
"It seems likely that while Roman sanitation may not have made people any healthier, they would probably have smelt better."
For his research, Dr. Mitchell looked at evidence of parasites from various excavations of Roman sites across what would have been the Roman Empire.
He studied evidence from "coprolites" - or fossilized feces - excavations of ancient latrines and human burials. He also studied evidence of parasites from combs and textiles.
Intestinal parasites, lice and fleas more prevalent in Roman period
Dr. Mitchell found intestinal parasites became more widespread when the Romans came.
And in another surprising finding, he also discovered that - despite the Romans' well-known habit of regular bathing - parasites that live on the body like fleas and lice were also more prevalent in the Roman Empire than in the times when bathing was far less common, such as during the Viking or medieval period.
He says he was surprised at this, since modern research shows that when you introduce toilets, clean drinking water and remove feces off the streets, the result is reduced risk of disease and parasite spread.
One might thus expect, suggests Dr. Mitchell, to see a similar result following the Romans' introduction of sanitation technology in Europe - such as reduction in whipworm and roundworm and other parasites. But, it seems that the opposite happened - so why?
While he did not investigate the causes, Dr. Mitchell speculates that one reason could be parasites spread more during the time of the Romans because they thrived in the warm, not-so-clean communal waters of their public baths. The water was not changed very often, and scum would have accumulated from human dirt and cosmetics, he suggests.
Feces as crop fertilizer, fermented fish sauce may have spread parasites
Another reason, suggests Dr. Mitchell, is the Romans used human excrement to fertilize crops. We know this can increase crop yields, but nowadays, we also know you need to compost human waste for several months first in order to destroy parasite eggs. If you spread human excrement without doing this, you spread parasite eggs that can survive in the crop, says Dr. Mitchell, who notes:
"It is possible that sanitation laws requiring the removal of feces from the streets actually led to reinfection of the population as the waste was often used to fertilize crops planted in farms surrounding the towns."
One example cited in the study is the case of fish tapeworm. Dr. Mitchell found eggs of the parasite were fairly widespread in Europe during the Roman period, compared with the Bronze and Iron Ages.
He suggests the reason could be because of the popularity of garum - a culinary sauce and medicine that the Romans made by fermenting raw fish, herbs, salt and flavorings. This was allowed to ferment in the sun and was not cooked, so did not kill off the tapeworm eggs.
Dr. Mitchell says the Romans traded garum right across the empire, and this probably boosted its effect as a "vector" for the spread of the parasite. He concludes:
"The manufacture of fish sauce and its trade across the empire in sealed jars would have allowed the spread of the fish tapeworm parasite from endemic areas of northern Europe to all people across the empire. This appears to be a good example of the negative health consequences of conquering an empire."
Although in Roman times, as today, intestinal parasites like whipworm were harmful to health, we are now also discovering they may have a use in treating disease because of the way they interact with the immune system.
For example, in June 2014, Medical News Today learned how sequencing the pig whipworm genome could lead to treatments for autoimmune diseases such as inflammatory bowel disease (IBD) and multiple sclerosis (MS).