The more relevant section would be actually this:

One possibility Mitchell offers is that it may have actually been the warm communal waters of the bathhouses that helped spread the parasitic worms. Water was infrequently changed in some baths, and a scum would build on the surface from human dirt and cosmetics. “Clearly, not all Roman baths were as clean as they might have been,” said Mitchell.
Another possible explanation raised in the study is the Roman use of human excrement as a crop fertilizer. While modern research has shown this does increase crop yields, unless the faeces are composted for many months before being added to the fields, it can result in the spread of parasite eggs that can survive in the grown plants.
“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,” said Mitchell.

It's actually the long known fact that towards the end of the Roman empire the bathhouse hygiene was hugely neglected and lots of diseases spread through them... thus I am bit skeptical about warm water hypothesis.

The part about the mandatory removal of feces leading to more (untreated) agricultural reuse is certainly feasible and a relevant topic to this very day.

However then the researcher is quoted saying:

This latest research on the prevalence of ancient parasites suggests that Roman toilets, sewers and sanitation laws had no clear benefit to public health. The widespread nature of both intestinal parasites and ectoparasites such as lice also suggests that Roman public baths surprisingly gave no clear health benefit either.

Which I think is a gross over-simplification and totally neglects the significant population increase in the cities and thus higher population densities that also took place in that time as far as I know. So I would rather say the interventions were not as effective as they have been assumed so far, but only through them it was possible to actually have larger cities in the first place.
And last but not least one should also not forget that the Romanization also brought a lot of trade and human travelling (incl. slave trade), which is generally related to the spread of diseases.

Recent research, conducted by Dr Piers Mitchell from University of Cambridge’s Archaeology and Anthropology Department and published in the journal Parasitology, is interesting and informative.

According to the research, archaeological evidence shows that intestinal parasites such as whipworm became increasingly common across Europe during the Roman Period, despite the apparent improvements the empire brought in sanitation technologies.

The Romans are well known for introducing sanitation technology to Europe around 2,000 years ago, including public multi-seat latrines with washing facilities, sewerage systems, piped drinking water from aqueducts, and heated public baths for washing. Romans also developed laws designed to keep their towns free of excrement and rubbish.

However, new archaeological research has revealed that – for all their apparently hygienic innovations – intestinal parasites such as whipworm, roundworm and Entamoeba histolytica dysentery did not decrease as expected in Roman times compared with the preceding Iron Age, they gradually increased.

The author, Piers Mitchell says (probably in a lighter vien): “It seems likely that while Roman sanitation may not have made people any healthier, they would probably have smelt better.”

More details can be seen at: www.cam.ac.uk/research/news/roman-toilet...20spread%20parasites


F H Mughal