Basic studies using animal models of human disease have shown that exposure to helminths can prevent colitis (1, 4-7), autoimmune diabetes (8,9), and autoimmune encephalitis (10, 11). Recently, investigators at the University of Iowa have shown that exposure to intestinal worms can reverse established colitis in IL-10 deficient mice (12). These studies suggest that exposure to helminths may be able to prevent or treat human disease.>>