During infection, an initial proinflammatory Th1-type polarized response is continuously triggered by Schistosoma-soluble adult worm antigen fractions, with elevated IFN-γ, TNF-α, and IL-12 levels, and then it is rapidly driven by egg antigens to a Th2-type dominant response (at approximately 6 weeks post-exposure). This evidence concerns the gene IFNG and infection.