Case study: Patient counters colitis with worms

Certain types of parasitic worms have become the subject of medical interest for their ability to influence the body’s immune system.

Dave Yasvinski 4 minute read March 18, 2021

A man travelled to Thailand in the hopes of curing his colitis in a very different way. Getty

Each week we comb through science journals to explore a baffling medical issue.

A 36-year-old California man wormed his way into medical history by opting for an unusual treatment for his worsening case of ulcerative colitis.

Short on options for his painful condition — and staring down the removal of his colon — the man sought out the services of parasitologist in Thailand who recommended ingesting 1,500 parasitic worm eggs, according to LiveScience. Remarkably, there was (some) method to the madness, as detailed in the man’s case study in the journal Science Translational Medicine in 2010.

Certain types of parasitic worms, also known as helminths, have become the subject of increasing interest for their ability to influence the way the body’s immune system responds to certain threats. Because ulcerative colitis causes an inflammation in the colon that kills healthy cells and leaves painful ulcers in their place, the hope was that the worms would supress the man’s immune system and decrease his discomfort.

Within a year of devouring the slimy snack, researchers discovered the man’s inflammatory bowel disease had improved to the point where treatment was no longer required. But before anyone starts adding plates of plump parasitic eggs to the menu, the researchers helpfully point out that although the worms had the desired effect, it was for a different reason then expected.

“There’s been a lot of interest in how helminth exposure affects autoimmunity and inflammatory disorders,” said Mara Broadhurst, one of the researchers into the case and (at the time) a doctoral student in immunology at the University of California, San Francisco. “We didn’t see a generalized suppression of inflammation, but rather a modified response.”

As the man’s body worked to expel the tiny trespassers, researchers suspect it also produced a thick mucus that covered the lining of his colon, providing temporary relief of symptoms. Although the treatment achieved the desired result, Broadhurst cautioned against it. “I don’t think that we’re at the stage where we can make this a general recommendation by any means,” she said. “We certainly aren’t at the stage where we understand which subsets of patients will benefit. With certain conditions, with particular defects … exposure to helminths can actually exacerbate inflammation.”

Indeed, swallowing thousands of helminths are more likely to cause colitis than cure it, said Peter Hotez, chair of the department of microbiology, immunology and tropical medicine at the George Washington University Medical Center in Washington, D.C. Hotez called trichuriasis — the specific type of parasitic worm the patient ingested — “the leading cause of colitis in hundreds of millions of children in developing countries.

“Ulcerative colitis goes through remissions spontaneously on its own and this could have been the case,” Hotez said. “Bottom line for me: Treating with worms is not a long-term effective strategy for IBD and is potentially very dangerous because you are actually causing a serious form of IBD by administering the worms.”


After the man’s symptoms returned in 2008, four years after his trip to Thailand, Broadhurst said he ate another 2,000 eggs to replenish the supply of parasites in his body. “As the worms reached the end of their lifespan, the inflammation came back and we had the benefit of seeing a second round of the same phenomenon,” she said.

Future research in this area should focus on treating patients by first extracting whatever beneficial compound — if any — is at play within the worms, rather than just consuming thousands of their eggs, Broadhurst said. Finding a way to promote the body’s mucus-making ability in the colon would also be a prudent area of study.

“That has a lot of promise for developing drugs that use those signaling pathways,” she said. “Ideally, the introduction of a live parasite wouldn’t be necessary for patients who want to pursue this form of treatment.”

Dave Yasvinski is a writer


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