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Dicrocoelium dendriticum

Dicrocoelium dendriticum. Presentation By Kristi Bjerke & Heather Lee. Background. Digenean trematode Part of the Dicrocoeliidae family of liver flukes Commonly known as the “lancet fluke” because of its bladelike shape. “small liver fluke”. Morphology. 6-10 mm long 1.5-2.5 mm wide

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Dicrocoelium dendriticum

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  1. Dicrocoelium dendriticum Presentation By Kristi Bjerke & Heather Lee

  2. Background • Digenean trematode • Part of the Dicrocoeliidae family of liver flukes • Commonly known as the “lancet fluke” because of its bladelike shape. • “small liver fluke”

  3. Morphology • 6-10 mm long • 1.5-2.5 mm wide • Pointed ends

  4. Geographic Distribution • Most of Europe and Asia • North America • South America • Australia • North Africa • alkaline soils that are favorable environments for reproduction and survival of the intermediate hosts

  5. Hosts • Definitive Host: sheep, cattle, goats, pigs, other ruminants, occasionally dogs, horses, and rabbits, rarely humans • Lives in the bile duct and gall bladder • Intermediate Host: snails, ants

  6. Life Cycle • Indirect • Approximately 6 months • Begins when a snail eats the parasite eggs • The eggs have miracidia which hatch and then penetrate the snail’s intestinal wall. • Within the digestive gland, the miracidia transforms into a mother sporocyst.

  7. Life Cycle Cont. • Mother sporocysts produce daughter sporocysts. • Second generation daughter sporocysts develop into cercariae • 3 months later, cercariae build up in the “lung” of the snail. • The snail deposits the cercariae (5,000) in a slimeball.

  8. Life Cycle Cont. • An ant eats the slime ball. • Metacercariae form within the ant’s abdominal cavity. • They then encyst and become infective to the definitive host. • One or two cercariae travel to the brain which causes a cataleptic cramp. • The cramp paralyzes the ant on a tip of grass when temperatures get below 15ºC. • This makes the ant more likely to be eaten by a ruminant.

  9. Life Cycle Cont. • After the ant is eaten, the metacercariae excyst in the gut of the definitive host. • They migrate to the bile duct and then the gall bladder. • Here they develop into mature flukes. • The flukes reproduce via cross fertilization or hermaphroditism • Eggs are released through the host’s feces.

  10. Life Cycle Diagram

  11. Pathogenesis • Hard to reproduce the life cycle in experiments • In the field there is often infection with other types of parasites with similar symptoms

  12. Pathogenesis continued • No penetration of the gut wall, liver capsule, or liver parenchyma as in fasciolosis • Clinical symptoms are not usually manifested even in heavy infections • However they may show anemia, edema, emaciation,and in advanced cases, cirrhosis, and scarring of the liver surface

  13. Diagnosis • adult dicrocoelia recovered in the liver post mortem • egg coprological (fecal) examination • Releasing of eggs can take 49-79 days upon infection

  14. Newer Diagnostic Techniques • Immuno-diagnostic techniques • Immuno-flourescence precipitation • Passive haemoagglutination test • Complement fixation • ELISA • All try and detect anti-Dicrocoelium antibodies

  15. Treatment • Anti-helminthic drugs like benzimidazole and pro-benzimidazole derivatives • As of 2002 no possible vaccines have been studied even though an anti-body dependent response has been found

  16. Control • Husbandry practices (don’t allow to graze at night or early in the morning) • Try and control snail and ant populations (difficult/expensive) • Test the soil to see whether it could be suitable for the intermediate hosts

  17. References • D. Otranto and D. Traversa. A review of dicrocoeliosis of ruminantsincluding recent advances in thediagnosis and treatment. Veterinary Parasitology 107 (2002) pp 317-335 • http://workforce.cup.edu/Buckelew/dicrocoelium_dendriticum_is_a_bi.htmhttp://www.ilri.org/InfoServ/Webpub/Fulldocs/X5492e/x5492e04.htm • http://www.spaltudaq.com/ • http://commons.wikimedia.org/wiki/Image:Benzimidazole_simple_structure.png • http://www.princetonol.com/groups/iad/bell/seddon.html • Janovy, John Jr. and Roberts, Larry S., Foundations of Parasitiology, 7th Edition, 2005

  18. THE END!

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