Opisthorchis viverrini, common name Southeast Asian liver fluke, is a trematode parasite from the family Opisthorchiidae that attacks the area of the bile duct. Infection is acquired when people ingest raw or undercooked fish. Infection with the parasite is called opisthorchiasis. Opisthorchis viverrini infection also predisposes the infected for cholangiocarcinoma, a cancer of the gall bladder and/or its ducts.