Trematoda
VMP 920Infection & Immunity II
Veterinary Parasitology
Fasciola hepatica
Large, leaf-like, liver/bile duct flukes Small anterior suckers Dendritic Intestines, Testes & Ovary
Life Cycle -- Aquatic Definitive Hosts
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
Geographic Distribution
Gulf Coast States, especially Florida
Pacific Northwest Not endemic in North Carolina
(WHY?)
Pathology
Acute 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
Diagnosis Fecal Sedimentation Clinical Signs:
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
Treatment Clorsulon (Curatrem)
Not licensed for breeding dairy cattle
8 day pre-slaughter withdrawal time
Albendazole Not licensed for breeding dairy
cattle 27 day pre-slaughter withdrawal
time
Control = break the life cycle
Control Snail 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
Zoonosis
Human Fascioliasis Europe, Africa, Cuba, South
America Potentially (US Gulf Coast, Florida, Pacific
NW)
Halzoun Ingestion of raw liver Adults attach to naso-pharynx Middle East
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.
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
Dicrocoelium dendriticum
Pathology & Diagnosis
Pathology (mainly in small ruminants) 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?)
Treatment & Control
Treatment Albendazole in high doses
Control Eradicate Ant hills & Snails May not be feasible