The problem i have with what you say is that the parasitic worms have adapted to use our defense mechanims and to alter ou immune system to their advantages, some parasitic worms even manage to survive in the blood (plasma) so if they manage to do that, how our immune system cells are supposed to manage to detect and to kill these multi cells organisms ?
Hygienists have made many claims without proofs, read the explanations of Herbert Shelton about parasitic worms and you will see how limited his understanding was. (I bet that he was infested by one or several kinds of parasitic worms)