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Release: August 9, 1999

UI researchers use intestinal worms to treat inflammatory bowel disease

IOWA CITY, Iowa -- Intestinal worms may hold the key to treating inflammatory bowel disease, according to University of Iowa Health Care researchers.

Inflammatory bowel disease refers to two conditions, ulcerative colitis and Crohn's disease, that are chronic diseases of intestines that cause abdominal pain, diarrhea and gastrointestinal bleeding. The diseases usually begin in people during their late teens and twenties and can last a lifetime.

UI researchers Joel Weinstock, M.D., professor of internal medicine; David Elliott, M.D., assistant professor of internal medicine; and Robert Summers, M.D., professor of internal medicine, noted that Crohn's disease has increased substantially in the United States and Europe over the past 60 years. Moreover, Crohn's disease and ulcerative colitis are rare in underdeveloped countries.

"These observations suggested that there is some critical environmental factor responsible for the development of inflammatory bowel disease," said Weinstock, director of the Digestive Disease Center at the UI Hospitals and Clinics. "We believed that the absence of the helminthic worms in the intestines was an important factor leading to the development of Crohn's disease and ulcerative colitis."

While the cause of inflammatory bowel disease remains undetermined, it is presumed to result from poor regulation of the intestinal immune system. Inflammatory cells in the gut protect us from its normal contents, and this highly effective chronic inflammation is tightly controlled. Thus, inflammatory bowel disease may result from inappropriately vigorous immune responses to normal intestinal bacteria, Weinstock said.

Helminthic is the scientific term that is used to describe various types of worms, some of which live in our gastrointestinal tract. More than one-third of the world's population carries one or more of these organisms. The prevalence of helminths is highest in warm climates where people live under less sanitary conditions.

The researchers noted that the rise of inflammatory bowel disease was preceded by a decrease in intestinal worm infections.

"These worms have been with us for more than 3 million years," Weinstock said. "Our intestinal immune systems have adapted to their presence. These worms normally dampen our mucosal immune response. Without them, we are more likely to produce powerful inflammatory substances that induce poorly controlled inflammation."

Animal studies conducted by Elliot supported this contention. He found that mice exposed to helminthic worms were protected from the development of inflammatory bowel disease.

Therefore UI researchers, led by Summers, organized a clinical study to determine if a helminthic parasite could be given safely to patients with inflammatory bowel disease. Six patient volunteers were given a single dose of microscopic parasite eggs. Four of the patients had Crohn's disease and two had ulcerative colitis. Each patient was seen in the clinic every two weeks using questionnaires and laboratory tests to closely monitor whether they had side effects or other health problems.

Interestingly, all of the patients improved substantially. This included a reduction in diarrhea and abdominal pain and improved energy level. The improvements lasted about four weeks, suggesting that additional doses might be needed. Preliminary results suggest that additional doses can be effective in prolonging the benefit of the treatment.

The UI researchers noted that the results are encouraging, but additional clinical studies are required to further establish this approach as being safe and effective. They are now organizing a double-blind, clinical trial with additional patients to further test the benefit of this unique treatment.