Fact-sheet: Liver fluke fasciola hepatica
Updated on 04/23/2018 at 9:20 AM
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Definition
Fasciola hepatica, or liver fluke, is a trematode parasite found in temperate countries, mainly in livestock farming regions.
The adult parasite lives in the bile ducts of certain herbivores (cattle, sheep) and its eggs are eliminated in the feces.
The freshwater snail Lymnaea serves as an intermediate host, after which larval forms leave the snail to attach to aquatic plants (watercress in particular).
Humans ingest the larvae when consuming contaminated raw vegetables; the parasite then crosses the gastric wall and Glisson's capsule to reach the bile ducts.
Clinical features
Invasive phase:- general malaise- epigastric and/or right upper quadrant pain- possible fever- painful hepatomegaly- urticaria
Biliary phase:- 3 to 6 months after exposure- clinical picture of acute cholangitis
Laboratory findings
Marked hypereosinophilia during the invasive phase.
Abnormal liver function tests with cytolysis.
Serology.
Ultrasound
Invasive phase: rounded hypoechoic lesions, sometimes confluent, predominating in the subcapsular region.
Biliary phase: flukes may be visible within dilated intrahepatic bile ducts.
CT
Invasive phase:- centimeter-sized hypodense lesions, sometimes confluent and arranged in a beaded pattern, extending from the subcapsular region toward the hilum- absence of bile duct dilation
Biliary phase:- intrahepatic bile duct dilation- oblong intraductal images corresponding to the parasite- possible perihepatic peritoneal reaction
Management
Antiparasitic treatment with triclabendazole.
Prevention: avoidance of wild watercress in the diet; washing watercress leaves is insufficient.