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Dicrocoelium dendriticum
Presentation ByKristi 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• Pointed ends
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
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
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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.
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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.
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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.
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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.
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Life Cycle Diagram
Pathogenesis
• Hard to reproduce the life cycle in experiments
• In the field there is often infection with other types of parasites with similar symptoms
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
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• However they may show anemia, edema, emaciation,and in advanced cases, cirrhosis, and scarring of the liver surface
Diagnosis• adult dicrocoelia
recovered in the liver post mortem
• egg coprological (fecal) examination – Releasing of eggs
can take 49-79 days upon infection
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Newer Diagnostic Techniques
• Immuno-diagnostic techniques
• Immuno-flourescence precipitation
• Passive haemoagglutination test
• Complement fixation• ELISA• All try and detect anti-
Dicrocoelium antibodies
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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
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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
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
THE END!