1. Dicrocoelium dendriticum
Presented by Kayla Schaefer and Julie Sobolewski

2. Dicrocoelium dendriticum
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Trematoda
Order: Plagiorchiida
Family: Dicrocoeliidae
Genus: Dicrocoelium
Species: D. dendriticum
Small flukes which inhabit the bile ducts of a wide variety of mammals
Small flukes which inhabit the bile ducts of a wide variety of mammals

3. Dicrocoelium dendriticum
Definitive Host:
Domestic and wild cattle, sheep, goats
Humans
Intermediate Host:
1st: Land snail (Cionella lubrica)
2nd: Ant (Formica fusca)
Geographical Distribution:
North/Central/South America
Europe
Asia
North/Central Africa
*Favors Dry Conditions*

4. Pop Quiz #1 Name one country this particular parasite is found.
(North/Central/South America, Europe, Asia, or North/Central Africa)
Name two definitive hosts for this parasite.
(Cattle, sheep, goats, or humans)

5. Morphology
Adult: 6-10mm by mm
Egg: 36-45µm by 22-30µm

6. Life Cycle

7. Life Cycle a.) Adult b.) Egg c.) Miracidium d.) Daughter sporocyst
e.) Mature Cercariae
f.) slime-balls
g-h.) transformation to metacercariae

8. Life within the Snail Eggs released in definitive host’s feces
Snail eats
Miracidium hatches from egg in intestine and penetrates gut wall
Transformation to mother sporocyst
Produce 1st and 2nd generation daughter sporocysts with cercariae through asexual reproduction
Cercariae accumulate
Cercariae escape through snail’s slimeballs

9. Life within the Ant Ant eats the cercariae-containing slime ball
Transform to metacercariae which encyst
Most remain in the hemocoel
1 or 2 migrate to subesophageal ganglion, “brainworms” (these are not infective)
Alter ant’s behavior
When temperatures drop in the evening ants climb to the tops of grasses/plants.
Mandible muscles spasm and lock onto the plant
Remain there till they are either eaten or the temperature warms and they resume normal behavior

10. Life within the Definitive Host
Infected ant is eaten by the host
D. Dendriticum excysts in the duodenum
Migrates upstream to the common bile duct and then the liver
Flukes mature in about 6 or 7 weeks
Reproduce by hermaphroditism or cross insemination
Eggs are produced and released in feces

11. Pop Quiz #2
What is the order the intermediate hosts come into play in this parasite’s life cycle?
(First the snail, then the ant)
What makes this parasite unique?
(It alters the behavior of the ant)

12. Pathogenesis/Clinical Signs
If present in small numbers, parasite does not have much affect on host
In severe cases when parasite is present in large numbers, following symptoms may occur:
Cirrhosis of liver (leading to decreased function)
Anemia
Edema
Emaciation
Appears to be no immunity

13. Diagnosis
Fecal floatation is one way to diagnose whether or not the parasite is present; however, the eggs are very small and not readily identified because they do not float well
Usually found at slaughter (find adults in liver)

14. Treatment Products: No treatment has been proven effective Valbazen
Thiabendazole
Triclabendazole
Albendazole – humans
Praziquantel – not in food animals
No treatment has been proven effective

15. Prevention/Control
Treat all animals exposed to infection (two or three times a year)
Control Intermediate Hosts
Calcium cyanamide molluscicide and chemical fertilizers
High costs
Ecological effects
Introduce turkeys, chickens or ducks to eat snails/ants
Cover ant nests with tree branches
Infected ants are generally found within 30 to 50 cm from their nest.

16. Prevention/Control
As humans we should avoid the urge to nibble or suck on grass which may have ants on it.

17. Public Health Concerns
Unless severe liver changes occur; infected animal is still edible
Humans have been infected but it is very rare
Economic losses seem less in D. dendriticum than in other flukes
Reports of Dicrocoeliosis have increased worldwide in the past 20 years

18. Pop Quiz #3
Why is a fecal floatation not the best way to diagnose this parasite?
(The eggs are small and do not float very well)
There is only one drug that is effective in getting rid of this parasite. True or False?
(False – no drug has been proven effective)

19. References
Associate Database. Dicrocoeliosis. Article obtained February, 12,
Dicrocoelium dendriticum – The Lancet Fluke. Dr. Chrissy O’Neill’s notes
Peacock, Dr. Andrew. Dicrocoelium dendriticum – The Lancet Fluke of Sheep. Published by Newfoundland and Labrodor Agriculture on April 14, Article obtained February 12,
Wikipedia. Dicrocoelium dendriticum. Obtained February 12,
Otranto, D., & Traversa, D. (2002/8/22). A review of dicrocoeliosis of ruminants including recent advances in the diagnosis and treatment. Veterinary Parasitology, 107(4),
Otranto, D., & Traversa, D. (2003/1). Dicrocoeliosis of ruminants: A little known fluke disease. Trends in Parasitology, 19(1),
Schmidt, G., & Roberts, L. (2005). Foundations of Parasitology (7th ed.). New York, NY: McGraw-Hill.