In the course of human civilization, gut worms have helped to train and balance the immune system, but a new hypothesis posits that their absence in the living environments of developed nations has led to higher rates of inflammatory bowel diseases such as Crohn’s disease and ulcerative colitis. In a study to test this theory (the “hygiene hypothesis”), researchers from NYU Langone Medical Center report that mice that are infected with intestinal worms exhibited a decrease in a bacterial species (Bacteroides) linked to increased risk for IBD, as well as an increase in a species (Clostridia) that acts to counter inflammation. Study co-senior investigator and parasitologist P’ng Loke, PhD, commented, “Our findings are among the first to link parasites and bacteria to the origin of IBD, supporting the hygiene hypothesis.” The study was published online last week in the journal Science.
The researchers believe that an immune response to the worms prompts the proliferation of Clostridia, which then either outcompete the Bacteroides for nutrition, or are themselves toxic to the Bacteroides. They suggest that it may be possible to isolate the chemical responsible for provoking the immune response, as a therapeutic approach to inflammation and IBD. An additional finding from the study was that people in rural parts of Malaysia, a region known to have low rates of IBD but a high incidence of worm infections, had significantly more Clostridia and fewer Bacteroides in their microbiomes than people comprising a nearby urban population. But people who were treated and dewormed had less Clostridia and more Bacteroides.
Read more about inflammatory bowel disease here.
Read a story about the new research here.
An article from the source journal analyzing the findings may be read here.