thanks for the input. You made some very good points.
was referring to intestinal parasites. hookworms i think are the only ones that can penetrate the skin
ascaris life cycle is to hatch, then larvae migrate to the lungs and then to the throat, where they are swallowed into the intestines to become adults. perhaps some stay in the lungs and become adults there, but that is rare and not part of their natural cycle.
i have heard of autoimmune disorders. perhaps i should have titled my OP " how to prevent self-induced systemic infections of intestinal parasites"