Trichobilharzia regenti, an avian schistosome that is capable of invading human skin, but not establishing a successful infection in humans, encodes a cysteine peptidase, cathepsin B2 (TrCB2 (GenBank: ABS57370.1)), which has elastinolytic properties and localizes to the acetabular glands of the parasite [13]. This evidence concerns the gene CTSZ and infection.