IL18 and infection: Similarly, while infection intensities with Ascaris lumbricoides decline along the development of Th2-biased parasite-specific responses53, the elevated expression of IL-12, STAT4 and IL-18 in ileum and liver as well as the elevated IFN-γ expression in lung tissue reported for Ascaris-infected pigs indicates an environment suited for the induction of IFN-γ expression in T and NK cells54,55.