The secretion of chemokines by Cryptosporidium-activated IECs is responsible for the recruitment of inflammatory monocytes, macrophages, and NK cells to the site of infection, and the presence of local IL-18 and IL-12 induces a synergistic activation of macrophages and NK cells to secrete high levels of IFN-γ in infected neonatal mice (170, 177). Here, IL18 is linked to infection.