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Release: Nov. 29, 2000

UI researchers advancing study of helminthic worms to treat inflammatory bowel disease

IOWA CITY, Iowa -- University of Iowa Health Care researchers are advancing their study of the use of helminthic therapy -- using specially prepared worm eggs -- to treat patients diagnosed with inflammatory bowel disorders that don't respond to standard treatments.

The UI researchers' preliminary work showed that helminthic therapy was promising in the treatment of refractory inflammatory bowel disease. The research team is now conducting additional studies to confirm its earlier findings.

"We are very pleased with the way our research is progressing," said Joel Weinstock, M.D., UI professor of internal medicine and director of the Digestive Diseases Center at the UI Hospitals and Clinics. "Our preliminary results showed that patients' health improves with treatment and that the therapy is safe."

The term inflammatory bowel disease refers to two conditions called ulcerative colitis and Crohn's disease, chronic inflammatory diseases of the intestines that cause abdominal pain, diarrhea and gastrointestinal bleeding. These diseases usually begin in people during their late teens to early 20s and usually last a lifetime. The frequency of Crohn's disease in the United States and Europe has increased substantially over the past 60 years. It is most prevalent in temperate regions that are highly industrialized.

Both Crohn's disease and ulcerative colitis are rare in underdeveloped countries. These observations suggest that there is some critical environmental factor responsible for the development of inflammatory bowel disease. The Iowa researchers believe that the absence of colonization of the intestines with helminthic worms is an important environmental factor favoring the development of Crohn's disease and ulcerative colitis.

UI researchers are conducting a placebo-controlled, double blind study of 64 patients diagnosed with Crohn's disease. A similar protocol is planned for patients with ulcerative colitis, and a third study that will enroll children diagnosed with inflammatory bowel disease is about to begin. The UI team is also collaborating with researchers in Europe and Canada to develop similar research trials on the international level.

Helminth is the scientific name that is used to describe various types of worms, some of which can live in the gastrointestinal tract. More than a third of the population of the world currently harbors one or more of these organisms. The prevalence of helminths is highest in warm climates where people live under less sanitary conditions. Children most frequently harbor helminthic infections because of their close contact with soil and suboptimal hygienic practices. Helminthic colonization was extremely common in children living in the United States before the 1930s.

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 our normal luminal contents. This highly effective chronic inflammation is tightly controlled. Inflammatory bowel disease may result from inappropriately vigorous immune responses to normal intestinal bacteria.

The rise in the frequency of inflammatory bowel diseases was preceded by a decrease in intestinal worm infections. Worms have been with us for more than three million years. Our intestinal immune systems have adapted to their presence. They normally dampen our mucosal immune response. Without them, we are more likely to produce powerful inflammatory substances that induce poorly controlled inflammation.

Animal experimentation conducted by David Elliott, M.D., UI associate professor of internal medicine, supported this contention. He showed that exposure of mice to helminthic worms protected them from the development of experimental inflammatory bowel disease.

Robert Summers, M.D., UI professor of internal medicine, organized a clinical study to determine if a helminthic parasite could be given safely to patients with inflammatory bowel disease. Eight patient volunteers ingest a single dose of microscopic parasite eggs. All the patients improved substantially. A series of patients receiving a dosing of the agent every three weeks have sustained remissions beyond one year.

The study of patients diagnosed with Crohn's disease is currently underway. To be eligible for that study, patients must be symptomatic and cannot have had extensive resections of the large or small intestine. If patients are not currently symptomatic, they can be withdrawn from their current medications to allow reactivation of the disease, and then they may enter the research trial. The studies of patients diagnosed with ulcerative colitis and children diagnosed with inflammatory bowel disorders are about to begin.

For more information, contact Robin Thompson, research coordinator, at (319) 356-3747.

University of Iowa Health Care describes the partnership between the UI College of Medicine and the UI Hospitals and Clinics and the patient care, medical education and research programs and services they provide.