IL33 and infection: As shown in Fig. 3a, b, IL-33 deficiency was transiently associated with attenuated type 2 inflammatory responses in the terminal ilea of IL-33−/− mice compared to WT mice, characterized by less infiltration of intestinal tissues by inflammatory cells and a wall thickness similar to that of non-infected mice at the sixth week of infection (t(3) = 5.897, P = 0.010; Fig. 3b).