IL-18 induces IFN-γ together with IL-12 or IL-15 and plays a role similar to IFN-γ [40,41,42], which is supported by our results showing that the expression of IFN-γ and IL-18 in late-staged schistosomiasis patients was significantly lower than that in chronic patients and healthy people. This evidence concerns the gene IL15 and schistosomiasis.