dicrocoelium dendriticum presentation by kristi bjerke & heather lee
TRANSCRIPT
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
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
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.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
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.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
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.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
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.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
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
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
• 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
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Newer Diagnostic Techniques
• Immuno-diagnostic techniques
• Immuno-flourescence precipitation
• Passive haemoagglutination test
• Complement fixation• ELISA• All try and detect anti-
Dicrocoelium antibodies
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
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
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
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!