London: The Romans are known for their apparent hygienic innovations, including public multi-seat latrines with washing facilities and sewerage systems, but a new study has found that intestinal parasites gradually increased in Roman times rather than decreasing. 

The study conducted by Piers Mitchell from the University of Cambridge's archaeology and anthropology department used ancient evidence for parasites in Roman times to assess "the health consequences of conquering an empire". 

Mitchell brought together evidence of parasites in ancient latrines, human burials and 'coprolites' -- or fossilised faeces -- as well as in combs and textiles from numerous Roman Period excavations across the Roman Empire. 

"Modern research has shown that toilets, clean drinking water and emoving faeces from the streets all decrease risk of infectious disease and parasites. So we might expect the prevalence of faecal oral parasites such as whipworm and roundworm to drop in Roman times -- yet we find a gradual increase," Mitchell said. 

Not only did certain intestinal parasites appear to increase in prevalence with the coming of the Romans, but it was also found that, despite their famous culture of regular bathing, 'ectoparasites' such as lice and fleas were just as widespread among Romans as in Viking and medieval populations, where bathing was not widely practiced. 

"Clearly, not all Roman baths were as clean as they might have been," Mitchell said. 

Some excavations revealed evidence for special combs to strip lice from hair, and delousing may have been a daily routine for many people living across the Roman Empire. 

"It is possible that sanitation laws requiring the removal of faeces from the streets actually led to reinfection of the population as the waste was often used to fertilise crops planted in farms surrounding the towns," the researcher said. 

The study found fish tapeworm eggs to be surprisingly widespread in the Roman Period compared to Bronze and Iron Age Europe. One possibility Mitchell suggests for the rise in fish tapeworm is the Roman love of a sauce called garum. 

"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," he said. 

The study was published in the latest issue of the journal Parasitology.