Fig. 1

Life cycle of Opisthorchis felineus. The eggs are shed in the biliary tree of fish-eating mammals and are passed with feces. They need to be ingested by freshwater gastropod snail, the first intermediate host, to develop into sporocysts, rediae, and free-swimming cercariae, the stage infective for the second intermediate host, cyprinoid fish [3, 7]. Humans and other fish-eating mammals may serve as a definitive host by ingesting raw, slightly salted, or frozen fish. Entering the host body, metacercariae infect the biliary tract of mammals, where they mature into adult worms, the sexual stage, over approximately 1 month. The lifespan of an adult liver fluke in the human body can reach over 20 years [7]