You probably thought leaching sounded bad. That’s not a parasite; this is a parasite! From Autoimmune Disorders Treatable With Worms and Bacteria Wall Fragments:
Some scientists have been advancing theories to explain some auto-immune disorders as being the result of lack of exposure to diseases that used to be common in the human past. Among the diseases suspected as being a consequence of lack of exposure to diseases are the painful digestive tract disorders inflammatory bowel disorder (IBD) and Crohn’s Disease. Joel Weinstock MD, a professor of internal medicine at University of Iowa, and colleagues have demonstrated that eggs of pig whipworm, when consumed by suffers of Crohn’s Disease (CD) and Ulcerative Colitis (UC), greatly reduce symptoms of those diseases.