I think there is alot of truth to Metaphysical healing that should be explored. I've always believed in mind over matter- (in my case, i have no mind, so it really doesn't matter..HAH!..... jus kidding)
But seriously, I feel you make a good point about that. I've prayed to God regarding my sinus parasites- and had dreams shortly after about the need to wash my sheets and pillow case. In the dream, I would see three globules that fell out of my nose or sinuses while I was asleep. When waking up that morning-- sure enough, there were three of the same little globules (eggs?) on the same areas near my pillow. I not only washed my sheets- I used a hepa-filter vaccum all over the bed and floor as well!!
People have to have more faith in the Divine in the most smallest matters to the largest matters. This whole discovery I had of parasites led me to a real cleansing process in more ways than one!