Researchers Say Case Study Shows Parasitic Worm Eggs May Have Use as Treatment
By Salynn Boyles
WebMD Health News
Reviewed by Laura J. Martin, MD
Dec. 1, 2010 -- It sounds made up, but it's true. A California man successfully treated his inflammatory bowel disease by self-medicating with parasitic worm eggs.
Now researchers at New York University say that by studying the man they have gained new insights into how worms promote intestinal healing.
The investigation could lead to potential targets for more conventional ways of treating bowel diseases like ulcerative colitis, parasitologist and researcher P'ng Loke, PhD, of NYU Langone Medical Center tells WebMD.
Research is also under way in the U.S. and Europe to determine if a pharmaceutical-grade worm egg liquid is useful for treating a range of health conditions, including Crohn's disease, multiple sclerosis, and even food allergies.
"We have known for a while that these parasitic worms could be beneficial for treating ulcerative colitis, but we haven't really understood why," Loke says. "By analyzing this patient, we may have found some answers."
Treating Bowel Disease With Worms
The patient, who preferred to remain anonymous, was in his mid-30s when he was diagnosed with severe ulcerative colitis in 2003.
He did not respond to steroid treatments, his condition progressed rapidly, and within a year his doctors told him that surgery to remove his colon or immune system-suppressing therapy were his only options.
Instead, after reading about early trials involving the parasitic pig whipworm Trichuris suis, the patient decided to infect himself with parasitic whipworm found in humans.
The main difference between the two worms is that the pig worm is eliminated from the body in just a few weeks, while the human version -- Trichuris trichiura -- makes its home in the large intestine for up to five years, Loke says.
"This patient did a lot of research," the investigator says. "He may be one of the smartest people I know. He was very aware of the risks."
Using worm eggs provided by a parasitologist in Thailand, the man ingested 500 eggs in late 2004 and 1,000 more eggs three months later.
Egg Treatment Led to Remission
His symptoms improved over the following months and by mid-2005 he had no symptoms at all and required no treatment for his disease.
He first contacted Loke in 2006, while Loke was working as a post-doctoral fellow at the University of California, San Francisco.
"He was in full remission at the time, and his main incentive was to stay in remission," Loke says.
The man agreed to a series of colonoscopies over the next several years, and Loke and colleagues analyzed blood and tissue samples during this time.
What they found was that the worms seemed to stimulate the production of mucus in the gut. The mucus contained a large number of T cells that produced a protein that is important in healing, known as interleukin 22.
Loke and colleagues believe that the mucus is produced in an effort to expel the worms from the gut. Instead of doing this it heals the lesions caused by the disease.
Experts: 'Don't Try This at Home'
The patient was lucky, Loke says, because the risks of deliberately colonizing the intestine with parasitic worms are not well understood.
"The patient reported no side effects, but that doesn't mean this would be the case for someone else," he says.
Joel Weinstock, MD, of Tufts University, agrees. Weinstock conducted some of the first pig whipworm research and is now involved in research to develop the pharmaceutical-grade worm treatment.
"It would not be wise for people to obtain eggs and take them the way this man did, because there is no way to be sure what you are getting," he says. "We are developing a defined agent that can be delivered in a predictable way."
Depending on the results of clinical trials that are now under way, a Trichuris suis egg drug could be available in a few years, he says.
Weinstock's worm research stemmed from the observation that conditions like ulcerative colitis and other inflammatory bowel diseases were common in countries where infection with parasitic worms was rare and almost unheard of in countries where worm infections are endemic.
This may be because the parasites actually have a calming effect on inflammation within the body to avoid eviction from their host home.
"These organisms have co-evolved with us for hundreds of thousands of years, and they have been part of our GI tract forever," Weinstock says.
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SOURCES: Broadhurst, M.J. Science Translational Medicine, Dec. 1, 2010; vol 2.P'ng Loke, PhD, assistant professor of medical parasitology, NYU Langone Medical Center.Joel Weinstock, MD, professor of immunology, Tufts University Sackler School of Graduate Biomedical Sciences, Boston.News release, NYU Langone Medical Center.
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