1. VMP 920 Infection & Immunity II Veterinary Parasitology
Trematoda

2. Fasciola hepatica Large, leaf-like, liver/bile duct flukes
Small anterior suckers
Dendritic Intestines, Testes & Ovary

3. Life Cycle -- Aquatic Definitive Hosts Ova Miracidia
Cattle, Sheep, Goats
Camelids
Ova
Miracidia
Snail 1st Intermediate Host
Pond / Puddle snails (aquatic)
Sporocysts and Redia
Cercaria
2nd Intermediate Host (or Environment)
Metacercaria
Aquatic or Semi-aquatic Vegetation
Young Flukes
Young flukes migrate from intestine via peritoneal cavity to the liver
Young flukes migrate through liver parenchyma before maturing in bile ducts
Prepatent period: about 2 months
Entire Life Cycle: 3-6 months

5. Geographic Distribution
Gulf Coast States, especially Florida
Pacific Northwest
Not endemic in North Carolina (WHY?)

6. Pathology Acute Chronic Due to migration of young flukes through liver
Severe liver damage, hemorrhage, inflammation
Usually results in sudden death, especially in sheep
Chronic
Due to adults in bile ducts
Loss of condition, weakness, hemolytic anemia (proline-induced), hypoproteinemia
Liver fibrosis, cholangiohepatitis
Calcification & Stenosis of Bile Ducts
Usually results in liver condemnation

9. Diagnosis Fecal Sedimentation Clinical Signs: Liver Enzyme Analysis
Acute: abdominal pain, unwilling to move, sudden death
Chronic: Loss of condition, weakness, signs of anemia, edema & ”bottle-jaw“.
Liver Enzyme Analysis
Necropsy
Herd History

11. Treatment Clorsulon (Curatrem) Albendazole
Not licensed for breeding dairy cattle
8 day pre-slaughter withdrawal time
Albendazole
27 day pre-slaughter withdrawal time

12. Control = break the life cycle

13. Control Snail Control Grazing Control Strategic Drug Control
molluscicides
adequate drainage of pastures
Grazing Control
Restrict access to wet areas
Strategic Drug Control
Ivermectin + Clorsulon (Ivomec Plus)
Early fall in Southern US

15. Zoonosis Human Fascioliasis Halzoun
Europe, Africa, Cuba, South America
Potentially (US Gulf Coast, Florida, Pacific NW)
Halzoun
Ingestion of raw liver
Adults attach to naso-pharynx
Middle East

16. Dicrocoelium dendriticum
Lancet Fluke
Translucent, lancet-shaped bile duct flukes.
Ventral sucker in anterior half of body.
Glodular Tandem Testes Posterior to the Ventral sucker, Globular Ovary posterior to testes.

17. Life Cycle -- Terrestrial
Definitive Hosts
Ruminants (Sheep, Goats, Cows)
Other Hosts (pigs, deer, woodchucks, rabbits, humans => zoonotic)
Ova passed in feces.
Miracidium remains in egg
Snail 1st Intermediate Host (ingests fluke egg)
Terrestrial Snail
Sporocysts
Cercaria in snail slime balls
2nd Intermediate Host (Ingests slime ball w/ larval fluke)
Metacercaria
Ants
Young Flukes
Young flukes migrate from intestine via peritoneal cavity to the liver
Young flukes migrate to the bile ducts & mature.
Prepatent period: 50 days
Adults can live 6 years or longer

18. Dicrocoelium dendriticum

19. Pathology & Diagnosis Pathology (mainly in small ruminants) Diagnosis
Non-pathogenic in younger animals
Bile duct hyperplasia, hepatic cirrhosis
Slow chronic progressive disease causing decreased productivity in older animals (ewes)
Diagnosis
Edema, emaciation in older stock
Ova in sedimentation
Geography:
Widely Distributed around the World
Northeast US & Canada
(Why not NC?)

20. Treatment & Control Treatment Control Albendazole in high doses
Eradicate Ant hills & Snails
May not be feasible