The Host with the Most

Parasites may defend against autoimmune diseases like multiple sclerosis, Crohn's disease

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Parasites may help the body protect itself against a host of autoimmune diseases like multiple sclerosis, inflammatory bowel disease and Crohn's disease. But before you go and swallow parasite eggs, keep reading.

In a growing body of evidence, studies suggest parasites, which evolved with humans over millions of years, may help regulate the immune system. Autoimmune disorders and diseases, in which the immune system attacks the body, are relatively rare in developing countries where infection with parasitic worms known as helminths is common.

Researchers, scientists and medical experts all caution against individuals intentionally infecting themselves with parasites, however, stressing the preliminary nature of the studies.

In a recent study, scientists using genomic tools and biopsies looked into the gut of one man stricken with ulcerative colitis (a type of inflammatory bowel disease) who had swallowed the eggs of an intestinal parasite. There they found evidence that suggested the worms’ presence stimulated mucus production, which disrupted the disease. (The patient's bowel disease had gone into remission after injesting some 1,500 parasite eggs obtained from a parasitologist in Thailand after medication failed to help).

“It’s not like the worm woke up one day and said, ‘What can I do to make you well?’" said Dr. Joel Weinstock, chief of gastroenterology at Tufts Medical Center, who was not a part of this study. "When you live close with something throughout evolution, and then you suddenly remove something, there can be consequences. Disturbing our intestinal worms, disturbing our intestinal bacteria, may modify or change our susceptibility to disease.’’

Scientists are looking at treatments that might mimic the parasite's role in apparently combatting autoimmune diseases.

And the worms' possible benefits may extend to allergy sufferers.

Lisa Ganley-Leal, assistant professor of medicine at Boston University School of Medicine, has studied people in Africa who suffer from schistosomiasis, a disease caused by a worm that lives in fresh-water snails. She discovered that individuals exposed to the disease have high levels of the antibody IgE (which usually causes allergies when it binds to cells), but the Africans she was studying had virtually no allergies. She later found that the worms appeared to "chop up" a protein that may prevent IgE from binding to cells, causing allergies.

It is estimated that up to 23.5 million Americans suffer from the 80 to 100 different types of autoimmune diseases. There are an additional 40 or so diseases thought to have an autoimmune basis.

Reviewed by: 
Review Date: 
December 10, 2010
Last Updated:
December 13, 2010