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