I was presenting on blogging at a medical conference recently when one of my co-panelists, a patient blogger, made reference to the fact that he once explored the use of parasitic worms to treat his Crohn's Disease. (Boy, did that ever get the audience's attention!) I was interested, then, to come across a Nature piece (subscription required) on the topic; in it, Tufts University gastroenterologist Joel Weinstock, MD, discusses worms' effects on the immune system and how infecting certain patients with them might actually help their health. He also shares the epiphany he had one day in the mid-90s, when pondering why "once-rare diseases, caused by autoimmunity" have become relatively common:
I was writing a review article at the time, on inflammatory bowel disease, and editing a book about parasites. That day, I was focusing on a chapter about how the 'evil' properties of intestinal parasites are often overblown. Considering the vast number of people who have carried them throughout history, the occurrence of associated disease is surprisingly infrequent. I was reminded of a classic teaching in parasitology, that a 'good' parasite imparts some advantage to its host — because if the host dies, so does the worm. Clearly, after thousands of years of co-evolution, the human immune system has evolved to handle the presence of most parasitic worms, which have, in turn, developed adaptations that enable them to live for years in a human host.
Was it possible that improved hygiene, by ridding our bodies of parasitic worms and beneficial bacteria alike, made way for the newer problem of immune-mediated diseases? And could reintroducing parasitic worms protect people against those diseases?
That brainstorm in the middle of a lightning storm has turned into an active area of research. Several ongoing clinical trials, in which patients with inflammatory bowel disease or multiple sclerosis are colonized with an intestinal worm, have produced early evidence that the treatment may be safe and effective.
The rest of the piece is worth reading, though perhaps not over lunch or dinner.