Hepatic Fascioliasis

Hepatic fascioliasis is infection of the liver and bile ducts by the liver fluke Fasciola hepatica (and F. gigantica), acquired by eating watercress, other aquatic plants or contaminated water. It has an acute hepatic phase and a chronic biliary phase.

It affects an estimated 2.4 million people worldwide, with hotspots in the Andes (Bolivia, Peru), Egypt, Iran and Vietnam, and sporadic cases in Europe. Livestock are the main reservoir.

Pathophysiology.

Metacercariae excyst in the duodenum, and larvae cross the gut wall and the liver capsule, tunnelling through the liver for 6 to 12 weeks (acute phase), then mature in the bile ducts (chronic phase), causing biliary obstruction, cholangitis, fibrosis and stones.

Acute phase: fever, right upper quadrant pain, hepatomegaly, urticaria, marked eosinophilia and weight loss. Chronic phase: biliary colic, cholangitis, jaundice, pancreatitis and cholecystitis, or no symptoms.

Red flags.

• Cholangitis.
• Obstructive jaundice.
• Subcapsular haematoma or haemorrhage (acute phase).
• Biliary stricture.

Acute phase: eosinophilia (often over 1.5 x 10^9/L), raised liver tests, serology (ELISA for Fasciola antigens), and CT showing hypodense, branching subcapsular tracks. Eggs are not in stool for 3 to 4 months. Chronic phase: oval eggs in stool, duodenal aspirate or bile, with serology. Ultrasound, magnetic resonance cholangiopancreatography or endoscopic retrograde cholangiopancreatography may show flukes or duct changes.

Differential diagnosis.

• Hepatic abscess.
• Toxocariasis and other tissue helminth infection.
• Hepatic schistosomiasis.
• Cholangiocarcinoma.
• Choledocholithiasis.
• Hydatid cyst.

Triclabendazole is the drug of choice for both phases. Praziquantel and albendazole are ineffective. Remove flukes endoscopically from the bile duct when obstruction is present. Treat cholangitis with antibiotics and drainage.

• Triclabendazole: 10 mg/kg orally as a single dose with food; repeat after 12 to 24 hours for severe infection (total 20 mg/kg); maximum 20 mg/kg in 24 hours; monitor for biliary colic during fluke expulsion, liver tests and QT interval; use caution in severe hepatic impairment; repeat stool examination at 3 and 6 months.
• Nitazoxanide (alternative when triclabendazole is not available): 500 mg orally twice daily with food for 7 days; maximum 1,000 mg daily; monitor liver tests; reduce in severe hepatic or renal impairment.
• Piperacillin-tazobactam (cholangitis): 4.5 g IV every 6 hours for 4 to 7 days after drainage; maximum 18 g daily; monitor renal function and counts; reduce for creatinine clearance under 40 mL/min.

Give analgesia for colic and corticosteroids for severe allergic reaction.

Monitoring. Eosinophil count and liver tests at 1, 3 and 6 months; stool examination at 3 and 6 months; repeat imaging for persistent lesions.

Referral and escalation. Infectious disease and pancreaticobiliary endoscopy.

Special groups. Children need weight based dosing. Pregnancy requires specialist advice.