Dicrocoelium dendriticum

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Dicrocoelium dendriticum

• Presentation By
• Kristi Bjerke
• Heather Lee

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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

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Morphology

• 6-10 mm long
• 1.5-2.5 mm wide
• Pointed ends

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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

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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 snails 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 ants 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 hosts feces.

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Life Cycle Diagram
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Pathogenesis

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

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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

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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 (dont 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

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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_den
  driticum_is_a_bi.htmhttp//www.ilri.org/InfoServ/W
  ebpub/Fulldocs/X5492e/x5492e04.htm
• http//www.spaltudaq.com/
• http//commons.wikimedia.org/wiki/ImageBenzimidaz
  ole_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

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THE END!