Infestation with benign parasitic worms is one possible explanation for the low incidence of autoimmune diseases and allergies in less developed countries and, conversely, for the sustained increase in such inflammatory conditions in more sanitized and hence “dewormed” industrialized societies.

Joel V. Weinstock, MD, of Tufts Medical Center in Boston, writing in Nature in an article titled “The Worm Returns,” reported that Native American reservations, where relatively high rates of infection with parasitic worms prevail, also have lower rates of inflammatory bowel disease, while Latinos born and raised in South America rarely develop the disease.

Although genetics are important in IBD, environment is even more so. “IBD was extremely rare at the turn of the 20th century and now it’s approaching a prevalence of one in 250 people,” Weinstock said. The key factor seems to be lack of exposure to protective organisms and the subsequent alteration of the development of the immune system.

See the article in Nature here. 

See a summary article on MedPage here.