IL13 and infection: Resistant animals produce high levels of interleukin 13 (IL-13) and associated T helper type 2 (Th2) cytokines in response to infection (Fig. 1), which are essential for parasite expulsion via mechanisms such as epithelial cell turnover and mucin production and muscle contraction (Khan et al., 2003; Cliffe et al., 2005; Hasnain et al., 2010; Chen et al., 2021).