Liver Fluke Lifecycle

The lifecycle of the liver fluke involves snails and fish as intermediate hosts. The adult worm deposits eggs containing miracidia into the biliary system of the infected mammal and these eggs leave the body in feces. The eggs are only able to hatch if they are consumed by certain types of snails, particularly of the genus Bithynia. After 6-8 weeks inside the snail, the miracidia develop into sporocytes, redia, and cercariae. The cercariae usually leave the snail to find any of approximately 95 species of Cyprinoid fish (such as carps and minnows), where they become infective cysts called metacercariae in muscle and connective tissues. Humans become infected when they consume infected raw fish. Dogs, cats, and rats are also commonly infected.

Cyprinoid fish

Inside the human host, the metacercariae excyst in the duodenum and move into the bile duct. They have scales and spines around their suckers and reach adulthood within one month. Liver flukes can persist for 25-30 years in the human host₁₁.

Typical Liver Fluke Lifecycle ₁₀

General Diagram of the Lifecycle of Class Trematoda, subclass Digenea₁₃

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