Fishing for a Cure
Diary of a Worm
Helminth therapy is based on what was originally termed the “hygiene hypothesis,” now sometimes called the “biome depletion theory.” Estimates of the number of cells in the adult body range from 10 to 100 trillion—and there are at least 10 times that many bacterial cells living within each of us. For every gene in our genome, there are 100 bacterial ones. This is our microbiome—and researchers are just beginning to examine how its composition can impact our health.
The biome depletion theory says that, as a result of better hygiene—afforded by post-industrial advances, such as toilets and water treatment facilities—people in developed countries are no longer exposed to, and therefore no longer harbor, some of the microscopic bacteria with which humans have historically had a symbiotic relationship. As a result, people in developed countries are missing some of the key microbes that keep the immune system in balance.
Normally, the immune system’s white blood cells help protect the body from harmful germs. To destroy these germs, the immune system produces antibodies, also known as immunoglobulins (Ig), to identify and neutralize the germs. It’s a complicated system, and not without misfires. In the case of food allergy, the immune system mistakenly decides that a food is harmful and creates antibodies in the attempt to render it harmless. In autoimmune disorders, the immune system makes antibodies when it mistakenly decides that the body’s own healthy tissue is harmful.
The biome depletion theory holds that reintroducing some long-lost little friends back into the body—in small numbers so as not to cause illness—will dampen inflammation. Exactly how helminths do this is not yet fully understood but they seem to activate immune regulatory mechanisms, as well as enhance mucosal barrier function.
The scientific research thus far is extremely encouraging. In 2005, Joel Weinstock, MD—now chief of the division of gastroenterology/hepatology at Tufts New England Medical Center—published a paper showing that in a randomized, double-blind, placebo-controlled trial (the gold standard in research), Trichuris suis ova (pronounced try-kyuriss soo-iss oh-vah) (TSO), which are microscopic pig whipworm eggs, was safe and effective in the treatment of ulcerative colitis, an inflammatory bowel disease.
Since then, evidence has been accumulating that helminths have the potential to treat other immune-mediated conditions, such as Crohn’s disease. One study has shown that, in patients with celiac disease, hookworm infection suppressed the inflammatory immune response after a gluten challenge, although it didn’t result in a clinically significant suppression of pathology. Studies are now underway to see if TSO can help conditions like multiple sclerosis and autism, both of which may involve an underlying immune dysfunction.
Next: Type of Treatment