Liver Flukes1

Liver Flukes • • • • •

Fasciola hepatica Fasciola gigantica Fascioloides magna Dicrocoelium dendriticum Clonorchis sinensis

Habitat: live in the duct system of the liver!

Between any three liver cells there is a bile capillary (Bile Canaliculus)

Flukes feed on epithelial cells, blood, and mucous caused by destruction of these cells!

Fasciola hepatica “The Sheep Liver Fluke” • Because sheep are the normal definitive host. • In places where sheep are not raised can be found in cattle. • Humans can become infected! 30 mm long

Fasciola hepatica “The Sheep Liver Fluke” • Distribution is cosmopolitan, and they are found primarily in agricultural animals. • In US and S. America commonly found in sheep and cattle.

Fasciola gigantica • Equivalent of F. hepatica in Southeast Asia, Hawaii, and Africa. • Basically big species of F. hepatica.

75 mm long

30 mm long

Fascioloides magna “Giant Deer Fluke or Giant Liver Fluke” • Found in deer, moose, and elk. • Sometimes in cattle, bison, sheep, goats, llamas, and pigs. • Never found in people! 100 mm long!

Fascioloides magna “Giant Deer Fluke or Giant Liver Fluke” • Domestic ruminants are aberrant hosts. • Common parasite in N. America especially in the Gulf coast, N.W., and Great Lakes area!

Dicrocoelium dendriticum The Lancet Fluke • Sheep, goats, deer, cattle, rabbits, and woodchucks. • Occasionally found in people.

10 mm long

Dicrocoelium dendriticum The Lancet Fluke • Cosmopolitan distribution but predominantly found in Eastern Europe.

Clonorchis sinensis “Chinese Liver Fluke or Oriental Liver Fluke” • Carnivorous animals are definitive hosts. • Dogs and cats (animals that eat fish-2nd IH) also occurs in people. • Also found in pigs, rats and camels (?)!

8-25 mm long

Clonorchis sinensis “Chinese Liver Fluke or Oriental Liver Fluke” • Orient – – – – –

Korea Thailand Vietnam Japan China

Life Cycles! • Liver fluke of ruminants and man: Fasiola hepatica, Fasciola gigantica and Fascioloides magna!

Life Cycles of Ruminant Liver Flukes • First intermediate hosts are snails in the family Lymnaeidae (pond snails): these are aquatic and semiaquatic snails.

Liver flukes of ruminants (aquatic life cycle).

Eggs of Fasciola hepatica

Eggs are 130-150 X 63-90 μm; golden brown, indistinct operculum, and unembryonated.

Miricidia develop in the egg (9-10 days) in the external environment, hatch and infect snail 1st IH

In the snail they develop sporocysts, 2 redia generations which release cercariae into the external aquatic environment! (five to seven weeks)

Cercariae encyst as metacercariae on aquatic vegetation!

Grass and water cress are typical 2nd IH

What happens in the DH

What happens in the DH • Juvenile worms penetrate the small intestine: enter the coelom and creep over the viscera until contacting the liver capsule!

What happens in the DH • Juvenile worms penetrate the small intestine: enter the coelom and creep over the viscera until contacting the liver capsule! • They then burrow into the liver parenchyma: wander about for almost two months feeding and growing.

What happens in the DH • Juvenile worms penetrate the small intestine: enter the coelom and creep over the viscera until contacting the liver capsule! • They then burrow into the liver parenchyma: wander about for almost two months feeding and growing. • Finally they enter the bile ducts: worms become sexually mature in another month and begin producing eggs. PPP- 8-10 wk. Live for 11 years!

Habitat Found In

Flooded Pastures!

Life cycle of Dicrocoelium dendriticum The Lancet Fluke Terrestrial life cycle!

Terrestrial land snails 1st IH

Ants 2nd IH Terrestrial land snails 1st IH

Up to 50,000 worms in 1 DH!

Ants 2nd IH Terrestrial land snails 1st IH

Life Cycle of Clonorchis sinensis “Chinese Liver Fluke” • Aquatic life cycle!

Snails 1st IH ingest eggs Miracidium Sporocyst Rediae

Snails 1st IH ingest eggs Miracidium Sporocyst Rediae Cercariae Encyst under scale or in muscle of freshwater fish 2nd IH

Metacercariae

Snails 1st IH ingest eggs Miracidium Sporocyst Rediae Cercariae Encyst under scale or in muscle of freshwater fish 2nd IH

Metacercariae Adult DH Egg production 1 month 3 months total Adults live 8 years

Eggs of Clinorchis sinensis • Vase shaped, 26-30 X 15-17 µm long, golden brown with a distinct operculum and abopercular knob.

Commercial Fish Ponds

What do liver flukes do to the host? • Seldom kill host; but do interfere with health of the host. • More significant to us because of agriculture. • If animals are infected, they are sick and don’t gain weight, won’t produce milk, etc. • In Gulf coast states up to 23% of meat is lost due to liver flukes!

Pathological Damage • Mechanical Damage: Worms get numerous and clog up bile ducts.

Pathological Damage • Mechanical Damage: Worms get numerous and clog up bile ducts. – Hard to digest. – If bile can’t get out it will kill liver cells (necrosis of liver cells). – Calcium deposits in bile ducts fibrosis, and lots of scar tissue eventually causing calcification of ducts, making them useless.

Fasciola hepatica

Pipestem fibrosis

Fasciola hepatica

White areas show cirrhosis in infected liver!

Big Picture for Major Pathology

FIBROSIS!

2ndary Pathology • Metacercariae penetrate intestine and migrate through body cavity (they don’t have a map!) through diaphragm and enter liver from outside. • Most make it but some become lost and become ECTOPIC INFECTIONS! • If encapsulated in wrong place can cause seizures!

Symptoms • Adult liver flukes feed on bile duct epithelium and suck blood, so symptoms are anemia, hypoalbuminemia, hypoproteinemia.

Bottle Jaw

Symptoms • Diarrhea, edema, and enlarged liver. • Lower abdominal pain and discomfort (can last for up to 10 yrs after treatment and no probability of getting reinfected!