This study indicates that S. haematobium infection is associated with a Th2-systemic response, but that this response differs between people carrying a patent infection (positive egg counts) and putatively resistant individuals (egg-negative lifelong residents with continued exposure to infective water) who have experienced previous infection (as evidenced by the presence of schistosome-specific IgA, IgG and IgE antibodies). This evidence concerns the gene IGHE and infection.