Exactly, colonoscopies that idiotic gastro doctors do will never find parasites, not E. Histolytica. Even Dr. Cahill writes that colonoscoies are contraindicated....
Mucus scraping is different, because you take nothing before that; and Dr. Cahill is one of the few, if not the only one who does it; but this practice is what is recommended by the best of the parasitology book, now abandoned by doctors.
They do not want to do the dirty work themselves; so they send it to some distant lab.....and then you know the story......