Dicrocoelium dendriticum is a small fluke that inhabits the bile ducts of a variety of mammalian hosts. It has a complex life cycle involving three hosts: land snails as the first intermediate host, ants as the second intermediate host, and various grazing mammals as the definitive host. D. dendriticum alters the behavior of infected ants, causing them to cling to plant tops at night where they are more likely to be eaten by grazing mammals. While it typically does not cause severe effects in hosts, heavy infections can lead to liver damage and other issues. Diagnosis is challenging as the eggs are small and difficult to detect in feces. No single treatment has proven fully effective against the parasite.

1. Dicrocoelium dendriticum
Www.RCVetS.com

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
Dicrocoelium dendriticum
• Small flukes which inhabit
the bile ducts of a wide
variety of mammals

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

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

5. Morphology
• Adult: 6-10mm by 1.5-2.5mm
• 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
1. What is the order the intermediate
hosts come into play in this parasite’s
life cycle?
(First the snail, then the ant)
2. 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:
– 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
1. Why is a fecal floatation not the best way to
diagnose this parasite?
(The eggs are small and do not float very well)
2. 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, 2007.
http://www.vin.com/Members/Associate/Associate.plx?DiseaseId=1499
• 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, 2004. Article obtained February
12, 2007. http://www.nr.gov.nl.ca/agric/animal_diseases/domestic/pdf/dicro.pdf
• Wikipedia. Dicrocoelium dendriticum. Obtained February 12, 2007.
http://en.wikipedia.org/wiki/Dicrocoelium_dendriticum
• 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), 317-
335.
• Otranto, D., & Traversa, D. (2003/1). Dicrocoeliosis of ruminants: A little known fluke
disease. Trends in Parasitology, 19(1), 12-15.
• Schmidt, G., & Roberts, L. (2005). Foundations of Parasitology (7th ed.). New York, NY:
McGraw-Hill.