Dicrocoelium dendriticum

1. Dicrocoeliumdendriticum Presented by Kayla Schaefer and Julie Sobolewski

2. Dicrocoelium dendriticum 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. 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) Dicrocoelium dendriticum

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 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 • 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: • 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, 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.