IL4 and schistosomiasis: Moreover, studies on population genetics with individuals living in endemic areas for schistosomiasis mansoni demonstrated that some polymorphisms in the SM1 genetic region, where several genes that code for type 2-immune cytokines, such as IL-3, IL-4, IL-5, IL-9, and IL-13, are located, are associated with susceptibility/resistance to schistosomiasis (80).