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[Opisthorchis felineus] [Opisthorchis viverrini]

Adults of Opisthorchis spp. are similar to, but often smaller than, Clonorchis sinensis.  Adults measure approximately 7 mm long by 1.5 mm wide in the human host (adults are slightly smaller in feline hosts).  Adults of Opisthorchis spp. differ from adults of Clonorchis in the shape of the testes.  The distribution of the vitelline glands is also different.  Both genera are similar, however, in having a ventral sucker (acetabulum) smaller than the oral sucker.  Adults reside in the bile ducts of the definitive host.

A	B

A: Adult of O. felineus.  Image courtesy of the Web Atlas of Medical Parasitology and the Korean Society for Parasitology.
B: Adult of O. viverrini.  Image courtesy of the Web Atlas of Medical Parasitology and the Korean Society for Parasitology.