Although the modulatory mechanisms induced by helminth infection that are capable of regulating allergic reactivity are not fully understood, experimental data obtained from mice models infected with S. mansoni or immunized with schistosome antigens and submitted to ovalbumin-induced asthma (72–74) and studies with asthma patients living in poly-helminthic endemic areas (75) showed that modulation of asthma inflammation was accompanied by induction of Treg and/or IL-10 production and reduction of Th-2 cytokine production, mainly IL-4 and IL-5, eosinophilia, and IgE levels. The gene discussed is IL4; the disease is asthma.