Sheep selected for low FEC control infection by the acquisition of anti-parasite antibody (Stear et al., 1999) driven byTh2 cytokines (Craig et al., 2014), and there is a significant genetic relationship between IgA antibody levels and the ability to control infection (Stear et al., 1997, Strain et al., 2002). This evidence concerns the gene CD79A and infection.