To reinforce the other repliers; people including doctors have deliberately infested themselves with hookworms to combat allergies. See https://en.wikipedia.or

To reinforce the other repliers; people including doctors have deliberately infested themselves with hookworms to combat allergies. See https://en.wikipedia.org/wiki/Helminthic_therapy https://en.wikipedia.org/wiki/Helminthic_therapy > Helminthic therapy, an experimental type of immunotherapy, is the treatment of autoimmune diseases and immune disorders by means of deliberate infestation with a helminth or with the eggs of a helminth. Helminths are parasitic worms such as hookworms, whipworms, and threadworms that have evolved to live within a host organism on which they rely for nutrients.