Parasitic Worm Eggs Improve Chronic Diarrhea

A new study claims that treating rhesus monkeys with the eggs of a parasitic helminth helped resolve their idiopathic chronic diarrhea (ICD), a condition similar to ulcerative colitis in humans.

Researchers at the New York University (NYU) Langone Medical Center (New York, NY, USA) and the University of California San Francisco (UCSF; USA) explored the effects of eggs from the whipworm Trichuris trichiura given to five monkeys with ICD. The idea came from observations that inflammatory bowel disease (IBD) is most common in countries where helminth infections have been mostly eradicated, and from direct evidence in animals and humans that helminth infections may protect against IBD.


The researchers found that the exposure to the whipworm led to clinical improvement in fecal consistency, accompanied by weight gain, in four out of the five treated monkeys. By quantifying bacterial pinch biopsies collected during colonoscopies before and after treatment using real-time PCR analysis, the researcher found changes to the composition of microbial communities attached to the intestinal mucosa following helminth treatment. For example, the genus Streptophyta was vastly increased in abundance in three out of five ICD monkeys relative to healthy controls, but was reduced to control levels post-treatment; by contrast, the phylum Tenericutes was expanded post-treatment. The study was published in the November 2012 issue of PLoS Pathogens.

“These findings suggest that helminth treatment in primates can ameliorate colitis by restoring mucosal barrier functions and reducing overall bacterial attachment, and also by altering the communities of attached bacteria,” concluded lead author PhD candidate Mara Broadhurst, and colleagues. “These results also define ICD in monkeys as a tractable preclinical model for ulcerative colitis in which these effects can be further investigated.”

Helminthic therapy involves the deliberate infestation with parasitic worms (or their ova), such as hookworms and whipworms. The therapy is targeted at, or available for, the treatment of Crohn’s disease, ulcerative colitis, IBD, and other conditions. Helminthic infection has emerged as one possible explanation for the low incidence of autoimmune diseases and allergies in less developed countries, together with the significant and sustained increase in autoimmune diseases in industrialized countries.

Related Links:
NYU Langone Medical Center
University of California San Francisco