RoughRomanMemes

Romans suffered from parasites in general for a variety of reasons - I'm addressing, specifically, the spread of fish parasites from the Mediterranean to the Atlantic, which is generally attributed to the wide transport of garum by the Roman Empire (and then passing through human feces, washed down through a river, and then into the Atlantic Ocean). Parasite eggs are generally more hardy than the parasites themselves, which allow them to survive harsher conditions until consumed by some unwitting Roman with no conception of micro-organisms.

That being said, and while I would like to clarify that composting was practiced by better-read Roman farmers and that generally animal waste was preferred, you're absolutely correct about human feces as fertilizer helping put Romans on the parasitic infection merry-go-round.