It's true you have to respect poop, and it's a natural thing for humans, but I doubt it's because of parasites.
I think it's more about hiding your presence from predators (the reason why cats hide their poop with soil and female dogs eat their puppies' poop, and sometimes they even keep eating it themselves when they're older).
Also, it's normal to be scared of parasites, but they're not simply a bad thing (sometimes they're really bad news, of course, but they're not pure evil or anything like that). In fact,
many autoimmune diseases can be easily cured by infecting with parasites, because the immune system gets some work to do and stops thrashing around.
It's designed to be too stong so that it can protect you even if there are parasites inside of you (they sedate it to protect themselves, and they also keep it busy, so it has to be strong to be able to multitask), but if you don't eat natural food with many living things inside (your body is prepared for it), it gets bored and becomes dangerous. Parasites and hosts evolve together, always.
As george101 said, all traditional communities (and all other species) deworm themselves with special foods when they feel they need it (or you can do it routinely if you want and you're not able to detect them).
I'm not saying we should eat poop sandwiches or foliar feed leaf crops with night soil, but it's a very important biomass and nutrients source. Making it go near trees' roots will nurture them safely for you, and biodigestors would be a very efficient way of sterilizing it (if you feel the need to do so) while producing energy and very nutrient-rich liquids and solids you could use in
aquaculture and in your fields.
Well, at least that's what I think.