THE MERCK MANUAL: The Merck Manual of Diagnosis and Therapymultimedia

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  • Fasciolopsiasis
  • Fasciolopsis buski life cycle.

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    Fasciolopsis buski life cycle.

    1. In the human host, unembryonated eggs are discharged into the intestine and pass out of the body with the feces.

    2. Eggs become embryonated in water.

    3. The eggs release miracidia, which penetrate a snail (intermediate host).

    4. In the snail, the miracidia develop into sporocysts, then rediae, and then cercariae.

    5. The cercariae are released from the snail.

    6. They encyst as metacercariae on aquatic plants and may be ingested by a mammalian host (human or pig).

    7. After ingestion, the metacercariae excyst in the duodenum and attach to the intestinal wall.

    8. There, they develop into adult flukes in about 3 mo.

    Image from the Centers for Disease Control and Prevention Image Library.

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