Fasciola hepatica Flashcards

Study Notes

Fasciola hepatica Overview

Also known as the liver fluke, a parasitic flatworm from the Trematoda class within the Platyhelminthes phylum.
Causes fascioliasis, impacting various mammals, including humans, with significant economic losses in livestock like sheep and cattle.

Habitat and Hosts

Primarily inhabits the bile duct of the liver.
Definitive hosts include sheep, cattle, and humans, while the intermediate host is fresh water snails (genus Lymnaea).

Transmission and Infection Route

Infection occurs when mammals ingest aquatic plants contaminated with encysted metacercariae.
Common transmission through consuming raw, fresh water vegetation or infected animal liver, particularly in the Middle East (halzoun).

Life Cycle of Fasciola hepatica

Adults live in the liver's bile ducts and start laying eggs 2-4 months post-infection.
Eggs hatch into miracidiae, which must find a snail host within 24 hours to survive.
Inside the snail, miracidiae transform into rediae, which develop into cercariae.
Cercariae encyst on aquatic plants, forming metacercariae, consumed by mammals, leading to infection in the small intestine.

Morphological Characteristics

Adult flukes are leaf-shaped, measuring 2-3 cm in length, equipped with oral and ventral suckers, a branched caecum, and a coiled uterus.
The genital formula includes one ovary and two testes.

Eggs and Diagnostic Features

Fasciola hepatica eggs are unembryonated, with a thin shell, operculated, and range from 130-150 µm by 63-90 µm, serving as the diagnostic stage.

Geographic Distribution

Widespread in rural areas, particularly in regions with cattle and sheep herding, affecting nearly 180 million people globally, with 2.4 million already infected.

Clinical Symptomatic Stages

Symptoms can be categorized into four stages: Acute Phase, Chronic Phase, Halzoun, and Ectopic Infection.

Acute Phase Symptoms

Rare in humans, symptoms may include fever, hepatomegaly, abdominal pain, vomiting, diarrhea, and anemia.

Chronic Phase Symptoms

More prevalent, characterized by biliary colic, abdominal pain, hepatomegaly, jaundice, and severe anemia in children.
Long-term inflammation can cause fibrosis and "pipestem liver," potentially leading to death.

Halzoun and Ectopic Infections

Halzoun occurs when consuming infected raw liver, causing pain, edema, and respiratory issues; the infection can persist for up to 10 years.
Ectopic infections are rare, affecting the peritoneal cavity, intestinal wall, lungs, or subcutaneous tissues.

Pathology and Clinical Symptoms

Damage caused by the flukes results from their migration through liver tissues, feeding on cells and blood.
Inflammation and edema in bile ducts are common due to the presence of the adult worms.

Description

Test your knowledge about Fasciola hepatica, commonly known as liver fluke, through this informative flashcard quiz. Understand its classification, habitat, and the disease it causes in mammals. Perfect for students studying parasitology and related fields.