Although the immune role of cytidine deaminase is not clear, Bouchut et al. [150] associated higher levels of its expression with enhanced resistance to echinostome infections and Ittiprasert et al. [148] observed up-regulation of cytidine deaminase in resistant and non-susceptible B. glabrata in early exposure to S. mansoni. Down-regulation of cytidine deaminase might therefore be associated with lower responsiveness to S. mansoni infections, particularly early in infection (down-regulation also noted at 3d, but not in shedding snails). This evidence concerns the gene CDA and infection.