Image: Fasciola LifeCycle 2013

Description: Immature eggs are discharged in the biliary ducts and in the stool The number 1. Eggs become embryonated in water The number 2, eggs release miracidia The number 3, which invade a suitable snail intermediate host The number 4, including the genera Galba, Fossaria and Pseudosuccinea. In the snail the parasites undergo several developmental stages (sporocysts The number 4a, rediae The number 4b, and cercariae The number 4c). The cercariae are released from the snail The number 5 and encyst as metacercariae on aquatic vegetation or other surfaces. Mammals acquire the infection by eating vegetation containing metacercariae. Humans can become infected by ingesting metacercariae-containing freshwater plants, especially watercress The number 6. After ingestion, the metacercariae excyst in the duodenum The number 7 and migrate through the intestinal wall, the peritoneal cavity, and the liver parenchyma into the biliary ducts, where they develop into adults The number 8. In humans, maturation from metacercariae into adult flukes takes approximately 3 to 4 months. The adult flukes (Fasciola hepatica: up to 30 mm by 13 mm; F. gigantica: up to 75 mm) reside in the large biliary ducts of the mammalian host. Fasciola hepatica infect various animal species, mostly herbivores.
Title: Fasciola LifeCycle 2013
Credit: www.cdc.gov/dpdx/fascioliasis/index.html
Author: CDC
Usage Terms: Public domain
License: Public domain
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