A coproantigen sandwich ELISA test was also developed using recombinant Opisthorchis viverrini cathepsin F (rOv-CF) for the diagnostic of O. viverrini infections, the conventional stool examination making the diagnostic difficult given the low intensity of the infection and intestinal coinfections, in the context of fatal cholangiocarcinoma caused by chronic and repeated infections with liver flukes [117]. The gene discussed is CTSF; the disease is infection.