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Dicrocoeliasis

[Dicrocoelium dendriticum]

Causal Agents

The trematode Dicrocoelium dendriticum, the lanceolate fluke.


Life Cycle

lifecycle

Ruminants are the usual definitive hosts for Dicrocoelium dendricitum, although other herbivorous animals, carnivores, and humans can serve as definitive hosts. Embryonated eggs are shed in feces The Number 1. The eggs are ingested by a snail The Number 2. Many species of snail may serve as the first intermediate host, including Zebrina spp. and Cionella spp. When the miracidia hatch The Number 2a, they migrate through the gut wall and settle into the adjacent vascular connective tissue, where they become mother sporocysts The Number 2b. The sporocysts migrate to the digestive gland where they give rise to several daughter sporocysts. Inside each daughter sporocyst, cercariae are produced The Number 2c. The cercariae migrate to the respiration chamber where they are shed in slime ball from the snail The Number 3. After a slime ball is ingested by an ant, the cercariae become free in the intestine and migrate to the hemocoel where they become metacercariae The Number 4. Many ants may serve as the second intermediate host, especially members of the genus, Formica. After an ant is eaten by the definitive host The Number 5, the metacercariae excyst in the small intestine. The worms migrate to the bile duct where they mature into adults The Number 6. Humans can serve as definitive hosts after accidentally ingesting infected ants The Number 7.

Geographic Distribution

Europe, northern Asia, America and northern Africa.

Clinical Presentation

Most infections are light and asymptomatic. In heavier infections, symptoms may include cholecystitis, liver abscesses and upper abdominal pain.

DPDx is an education resource designed for health professionals and laboratory scientists. For an overview including prevention and control visit www.cdc.gov/parasites/.

  • Page last reviewed: May 3, 2016
  • Page last updated: May 3, 2016
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