Trematode infections. Opisthorchiasis, clonorchiasis, fascioliasis, and paragonimiasis.

The parasitic diseases of the liver and lung are caused by trematodes or flukes--Opisthorchis viverrini, O. felineus, Fasciola hepatica, and Paragonimus westermani. Humans get infected by eating the second intermediate host of the fluke, for example, fish, crab, or water plant. The disease runs a chronic course. The diagnosis is made by the recover of eggs in stools or sputum, or by serodiagnosis. Praziquantel is the drug of choice except in falcioliaisis.