High IgE levels (to heterogeneous schistosomula and adult antigens, as well as more specific antigens, such as Sm22) and high IgE/IgG4 ratios, are well-established correlates of human resistance to schistosomiasis, while IgG2, IgG4, and IgM are negatively correlated (190–, , , 194). This evidence concerns the gene IGHE and schistosomiasis.