As with other helminths, infection with the cestode T. crassiceps induces strong and long-lasting Th2-polarized immune responses, and high systemic levels of IL-4, IL-5, IL-10, IL-13, IgG1, and IgE as well as low NO, IL-1β, IL-12, IL-15, IL-18, IL-23, TNF-α, and IFN-γ serum concentrations are achieved. This evidence concerns the gene IL4 and infection.