The Barefoot Herbalist can give you all of that information. Parasites, etc., live on our junk so that is why we need to clean up and improve our diets so that there is little junk there. As long as our 'biological terrain' has lots of junk in it, then tapeworms, etc., have lots to eat and will make their home there.
As I say, go over to BH's forum and you will learn loads.