Opisthorchiasis By Chelsea Marie, PhD, University of Virginia; William A Petri, Jr, MD, PhD, University of Virginia School of Medicine Reviewed / Revised Aug 2021 | Modified Sep 2022 View Patient Education Topic Resources Opisthorchis Life Cycle Opisthorchiasis is infection with Opisthorchis viverrini (Southeast Asian liver fluke) or O felineus (cat liver fluke), which are acquired by eating infected raw or undercooked fish that contains infectious metacercariae (encysted stage).