As the Worm Turns: For 200,000 years, we humans have hosted parasitic hookworms and whipworms in our intestines. Until recently, that is: when antibiotics and better sanitation effectively “dewormed” much of the developed world. Coinciding neatly, was a perplexing rise in autoimmune diseases of the gut, like inflammatory bowel disease (IBD) and Crohn’s disease. Scientist Joel Weinstock wondered if there was a connection?
Whip it!: He began by treating mice with IBD. Animals fed enteric worms recovered from the disease. To test this therapy in humans, he chose Trichuris suis, a whipworm that typically infects pigs but causes no illness if swallowed by pig farmers. A patient with Crohn’s disease volunteered to swallow 2,500 tiny eggs (in a sports drink!) and his disease symptoms improved. Now, clinical trials are underway with many more patients, and the egg harvesting method has been approved by the FDA and European Medicines Agency. Other immune related diseases are also being tested: multiple sclerosis, autism, ulcerative colitis, psoriasis, and type 1 diabetes.
Old Friends Hypothesis: The idea behind the treatment is that our immune system can only become fully effective if stimulated by exposure to microorganisms and parasites that have low levels of pathogenicity, and which have coexisted universally with human beings throughout our evolutionary history. Autoimmune disease is caused by excessively high TH1 response, which is kept in check by an opposing TH2 response set off by infections. Of course, vaccines and public hygiene have greatly reduced disease and improved the quality of life in the past 100 years. The idea is to reintroduce some organisms into people in a controlled way, to improve human health without causing infectious disease.
Image: Trichuris whipworms, via http://www.stanford.edu/group/parasites/ParaSites2005/Trichuris/Untitled-12.htm