Despite their sanitation inventions, the Romans still had a lot of intestinal parasites – even more than the ages before them. Archaeological research shows that despite the introduction of latrines (toilets) and washing facilities, intestinal worms were still a huge problem in Rome and across the empire.

Research has shown that whipworm, roundworm and dysentery did not decrease in number during Roman times, even though it is widely understood they were a particularly hygienic people. Fish tapeworm eggs were very widespread, with even bigger numbers than the Bronze Age and the Iron Age.

"I expected to see a drop in the number of [parasites] following the introduction of Roman latrines and sewers, but there was no evidence of such a drop in the archaeological data," Piers Mitchell, the lead author of the report, told IBTimes UK. "However, one interesting finding from this study was that fish tapeworm seems to have increased its geographic distribution during the Roman Period, from two countries in the Bronze and Iron Age, to six countries in the Roman Period."

Mitchell, from the University of Cambridge, suggested the rise in fish tapeworms are associated to the Roman culinary habits. In particular, their love for the sauce called "garum".

Garum was not cooked and was instead allowed to ferment in the sun. It was also shipped across the entire empire, which at its maximum, stretched five million kilometres; the equivalent of running a marathon 119,000 times consecutively.

"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," said Mitchell. "This appears to be a good example of the negative health consequences of conquering an empire."

Fish tapeworm egg
Scientists found fish tapeworm eggs as far as Turkey Piers Mitchell

The research, published in Parasitology, also speculates on why other parasites did not decrease in number. It suggests the warm, communal baths may have a large role to play in spreading the worms. The water in the baths was not changed very often, and dirt would be allowed to build up on the surface.

The use of human faeces as crop fertiliser may have spread parasites, too. While excrement is beneficial for plants, it has to be composted for months before being applied to field – or risk spreading nasty parasites.

Researchers aim to build on this study by investigating the abundance of parasites across the world, through time.

Mitchell said: "I am interested in studying infectious diseases in different cultures right throughout human history, in order to discover which aspects of past lifestyle affected the risk of contracting infections in our ancestors.

"I currently have a number of interesting projects under way looking at archaeological evidence for parasite infections at a range of Roman sites, and also in historic and prehistory populations around the world."