NEW YORK, April 15 — Worm infection may protect against inflammatory bowel diseases, according to a recent study, leading researchers to suggest a lack of exposure to worms in the overly-sanitized modern world is increasing cases of the conditions.
Researchers at New York University suggest exposure to worms, or at least to immune chemicals produced when worms are present in the gut, could prevent IBD in some people.
The worms trigger reactions in the gut microbiome — the production of specific bacteria, clostridia, which help counter inflammation — but in their absence, the researchers found inflammation occurs, leading to IBD.
The researchers say the findings support the hygiene hypothesis, a theory that too-clean homes, pervasive overuse of hand sanitizers and a general avoidance of “germs,” has contributed to changes in the collection of bacteria in the gut essential to bodily function.
“Our study could change how scientists and physicians think about treating IBD,” Dr. Ken Cadwell, an assistant professor at the New York University’s Skirball Institute of Biomolecular Medicine, said in a press release. “Patient testimonials and anecdotes lead many to think that worms directly cure IBD, while in reality, they act on the gut bacteria thought to cause the disease.”
For the study, published in the journal Science, researchers found mice with intestinal worms had a thousand-fold decrease in a group of bacterial species called bacteroides linked in previous studies to higher risk for IBD. Clostridia, at the same time, were found to have 10 times the presence in worm-infected mice.
The clostridia compete with bacteroides for nutrients, or kill them by releasing toxins, further decreasing their number in the intestine and counteracting their inflammatory effects.
Cadwell said the findings support the hygiene hypothesis, as have studies in countries where worm infestation remains more common because of a lower emphasis on sterilizing every environment.
“Our findings are among the first to link parasites and bacteria to the origin of IBD, supporting the hygiene hypothesis,” said Dr. P’ng Loke, an associate professor at NYU, who said the study may also lead to a greater understanding of the role the gut microbiome plays in other inflammatory conditions and autoimmune diseases such as multiple sclerosis, rheumatoid arthritis and type 1 diabetes.