Life Cycle and Pathogenesis of Liver Flukes

Study Notes

Life Cycle

Adult stage: Liver flukes (Fasciola hepatica) live in the bile ducts of the liver, where they feed on bile and attach to the duct walls.
Egg stage: Adult flukes lay eggs that are excreted in the feces of infected animals.
Miracidium stage: Eggs hatch into miracidia, which infect aquatic snails (intermediate hosts).
Sporocyst stage: Miracidia develop into sporocysts, which produce cercariae.
Cercariae stage: Cercariae emerge from snails and infect vegetation.
Definitive host: Grazing animals, including humans, ingest infected vegetation and become infected.

Pathogenesis

Migration: After ingestion, larvae migrate through the intestinal wall and peritoneal cavity, causing inflammation and tissue damage.
Hepatic migration: Larvae penetrate the liver, causing hemorrhage and necrosis.
Bile duct migration: Mature flukes migrate to the bile ducts, where they feed and reproduce, causing obstruction and inflammation.
Immune response: Host immune response leads to granuloma formation and fibrosis.

Treatment Options

Triclabendazole: Effective against adult flukes, but not against immature stages.
Bithionol: Used to treat fascioliasis, but has toxic side effects.
Praziquantel: Effective against all stages of the parasite, but may require repeated doses.
Supportive care: Rest, hydration, and nutritional support may be necessary to manage symptoms.

Clinical Symptoms

Acute phase: Fever, abdominal pain, diarrhea, and anemia.
Chronic phase: Fatigue, weight loss, anemia, and hepatomegaly.
Biliary obstruction: Jaundice, dark urine, and pale stools.
Complications: Liver abscesses, cholangitis, and secondary bacterial infections.

Description

Learn about the life cycle of liver flukes, including their adult, egg, miracidium, sporocyst, and cercariae stages. Understand the pathogenesis of fascioliasis, including migration, hepatic migration, and bile duct migration. Discover treatment options and clinical symptoms.