Fasciola hepatica is one of a number of trematode or fluke infections of the gastrointestinal tract and/or liver. The infection is common in sheep, goats and cattle in many parts of the world but is rare in humans. The life-cycle begins with the ingestion of metacercariae that are encysted on freshwater plants such as watercress. Thereafter, larvae excyst in the small intestine, penetrate through the gut wall into the peritoneal cavity and subsequently pass into the liver through the liver capsule. The young flukes then penetrate intrahepatic bile ducts, mature in the biliary system and produce eggs. These eggs are then excreted in feces and, after reaching fresh water, undergo a period of maturation prior to the release of miracidia. Motile miracidia can then enter a suitable snail and develop into a sporocyst that eventually releases numerous cercariae that encyst on freshwater plants. Mature F. hepatica within the bile duct are usually leaf-shaped and measure approximately 3 cm × 1 cm × 1 mm in size. In humans, infections are often asymptomatic but symptoms can occur during the hepatic migratory phase or because of the presence of adult flukes in the bile duct. In the latter setting, symptoms include abdominal pain, obstructive jaundice, cholangitis and, on rare occasions, pancreatitis. The diagnosis of Fasciola infection is usually based on an antibody (ELISA) test as eggs are often difficult to detect in feces. Countries with significant numbers of human infections include Bolivia, China, Ecuador, Egypt, France, Iran, Peru and Portugal.
The images shown below were from a 73-year-old woman who was investigated because of a 3-day history of abdominal pain that was accompanied by pruritis and jaundice. She had previously had a cholecystectomy for gallstones. Blood tests revealed an elevated serum level of bilirubin (11 mg/dl, 188 µmol/l), and alkaline phosphatase (300 U/l). An abdominal ultrasound study showed dilatation of the bile duct (12 mm). At endoscopic retrograde cholangiopancreatography, a filling-defect was identified in the bile duct and she was treated by endoscopic sphincterotomy. An adult fluke was extracted from the bile duct using a Dormia basket (Figure 1) and was subsequently retrieved within the basket for pathological evaluation (Figure 2). Thereafter, she was treated with a single dose of triclabendazole. Her liver function tests subsequently returned to normal.