Opisthorchiasis

**Definition:** A disease caused by an infection with the parasitic worm Opisthorchis. This disease is commonly asymptomatic. In mild cases, this disease may present with dyspepsia, abdominal pain, diarrhoea, or constipation; in severe cases, this disease may present with hepatomegaly and malnutrition; in rare cases, this disease may present with cholangitis, cholecystitis, and cholangiocarcinoma. Transmission is by ingestion of infected undercooked freshwater fish. Confirmation is by of identification Opisthorchis in a faecal sample.