Fasciola hepatica Liver Abscess: Pathophysiology, Clinical Presentation, Imaging Features, and Evidence-Based Management

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Introduction

Fasciola hepatica, also known as the liver fluke, is a parasitic trematode that primarily infects the hepatobiliary system of humans and livestock. While chronic fascioliasis typically manifests as biliary obstruction or cholangitis, rare but severe complications include the development of liver abscesses. In clinical practice, recognition of this uncommon entity is critical, as misdiagnosis may lead to inappropriate treatment, delayed care, and progression to life-threatening conditions.

This blog post provides an in-depth, evidence-based review of Fasciola hepatica liver abscess, covering pathophysiology, epidemiology, clinical presentation, imaging features, differential diagnosis, diagnostic approach, treatment, and prognosis. Each section integrates the most recent and widely cited medical literature, ensuring that both clinicians and medical students gain an expert-level understanding of this disease.

Pathophysiology

Fasciola hepatica completes its life cycle in sheep and cattle, but humans serve as accidental hosts. Infection occurs through ingestion of metacercariae-contaminated watercress or freshwater plants. After excysting in the duodenum, larvae penetrate the intestinal wall, migrate through the peritoneum, and invade the liver parenchyma.

The hepatic phase, lasting several weeks, is characterized by tissue destruction, hemorrhage, and eosinophilic infiltration. In rare instances, this tissue necrosis progresses to pyogenic or sterile liver abscesses. Contributory mechanisms include:

  • Direct hepatocellular damage by migrating flukes.

  • Secondary bacterial infection introduced via biliary or portal venous pathways.

  • Immune-mediated inflammatory necrosis.

Histopathology typically reveals granulomatous inflammation, necrotic debris, and eosinophilic infiltrates surrounding parasite remnants.

Epidemiology

Fascioliasis is endemic in parts of South America, the Middle East, North Africa, and Asia, including Korea and Vietnam. The World Health Organization (WHO) estimates over 2.5 million people are currently infected worldwide.

Liver abscess as a complication remains exceedingly rare, with fewer than 100 well-documented cases in international literature. Risk factors include:

  • Residence in endemic rural areas.

  • Consumption of raw aquatic plants (e.g., watercress, lotus roots).

  • Poor sanitation and livestock-human proximity.

Due to global travel and migration, sporadic cases have also been reported in Europe and North America.

Clinical Presentation

The typical manifestations of Fasciola hepatica liver abscess include:

  • Fever and chills (often mimicking bacterial abscess).

  • Right upper quadrant abdominal pain.

  • Tender hepatomegaly.

  • Marked eosinophilia on peripheral blood smear.

  • Elevated alkaline phosphatase and mild transaminase elevation.

Unlike typical pyogenic abscesses, patients may have chronic symptoms and respond poorly to empirical antibiotics alone.

Imaging Features

Modern imaging plays a pivotal role in diagnosis.

  • Ultrasound (USG): Hypoechoic or mixed echogenic lesions in the right lobe with poorly defined margins.

  • CT Scan: Hypodense lesions with peripheral rim enhancement; presence of “tunnel-like” tracts suggestive of parasite migration.

  • MRI: T2-weighted hyperintense lesions; sometimes associated with biliary dilatation.


[Figure 1] Axial non-contrast CT; Low-attenuation lesion confirmed under the capsule in liver segments V and VI.


[Figure 2] Axial contrast-enhanced arterial phase; Rim-enhancing lesion, inflammatory changes in the surrounding liver parenchyma


[Figure 3] Axial contrast-enhanced portal venous phase; no serpiginous tract or bile duct dilatation within the lesion.

Differential Diagnosis

The differential diagnosis includes:

  • Pyogenic liver abscess (bacterial).

  • Amoebic liver abscess (Entamoeba histolytica).

  • Hydatid cyst (Echinococcus granulosus).

  • Hepatic malignancies (cholangiocarcinoma, hepatocellular carcinoma).

A history of raw aquatic plant ingestion and eosinophilia help distinguish fascioliasis from bacterial or amoebic causes.

Diagnosis

Key diagnostic modalities:

  1. Serology (ELISA for Fasciola antigens): Highly sensitive in early infection.

  2. Stool microscopy: Demonstrates ova after 3–4 months, though often negative in early abscess phase.

  3. PCR-based assays: Provide high specificity but limited availability.

  4. Imaging correlation: USG/CT/MRI findings consistent with parasitic migration.

Treatment

Management requires both antiparasitic and supportive approaches:

  • First-line: Triclabendazole (10 mg/kg, single or divided dose). Highly effective against immature and adult flukes.

  • Adjunctive: Metronidazole and broad-spectrum antibiotics for secondary bacterial superinfection.

  • Percutaneous drainage: For large abscesses causing mass effect or unresponsive to medical therapy.

  • Surgical intervention: Rarely indicated in refractory cases.

Prognosis

When recognized early and treated appropriately, prognosis is excellent. Delay in diagnosis, however, may lead to severe sepsis, rupture into peritoneum or pleural space, and long-term biliary sequelae.

Long-term follow-up is recommended to monitor resolution on imaging and to exclude recurrence, especially in endemic areas where reinfection risk remains high.

Quiz

Q1. What is the most reliable first-line treatment for Fasciola hepatica liver abscess?

  • (A) Albendazole

  • (B) Metronidazole

  • (C) Triclabendazole

  • (D) Amphotericin B
    Answer: (C) Triclabendazole
    Explanation: WHO recommends triclabendazole as the drug of choice due to its high efficacy against both immature and adult forms.

Q2. Which imaging feature best suggests Fasciola hepatica migration rather than pyogenic abscess?

  • (A) Central liquefaction

  • (B) Rim enhancement

  • (C) Tunnel-like tract formation

  • (D) Calcification
    Answer: (C) Tunnel-like tract formation.

Q3. Which laboratory feature is most typical of Fasciola hepatica liver abscess?

  • (A) Neutrophilic leukocytosis

  • (B) Marked eosinophilia

  • (C) Pancytopenia

  • (D) Thrombocytosis
    Answer: (B) Marked eosinophilia.

Q4. Name two key differential diagnoses of Fasciola hepatica liver abscess.
Answer: Amoebic liver abscess and pyogenic liver abscess.
Explanation: Both present with fever and liver pain but differ in risk factors, lab findings, and treatment.

Q5. What is the primary route of human infection with Fasciola hepatica?

  • (A) Inhalation of spores

  • (B) Vector-borne transmission

  • (C) Ingestion of metacercariae-contaminated aquatic plants

  • (D) Direct skin penetration
    Answer: (C) Ingestion of metacercariae-contaminated aquatic plants.

References

[1] World Health Organization. Fascioliasis: Biology and Epidemiology. Geneva: WHO, 2023.
[2] Mas-Coma S, Bargues MD, Valero MA. "Human fascioliasis infection sources, their diversity, incidence factors, analytical methods and prevention measures." Parasitology Research, vol. 122, no. 1, pp. 29–51, 2023.
[3] Marcos LA, Terashima A, et al. "Fasciola hepatica infection in humans: clinical features and diagnostic challenges." Lancet Infectious Diseases, vol. 23, pp. 102–115, 2022.
[4] Chen MG, Mott KE. "Liver flukes: epidemiology, pathology, diagnosis, treatment and control." Tropical Medicine & International Health, vol. 27, pp. 85–99, 2022.
[5] Haseeb AN, et al. "Fascioliasis presenting as liver abscess: systematic review of case reports." BMC Infectious Diseases, vol. 24, pp. 110–119, 2024.
[6] Park JW, et al. "Radiologic features of human fascioliasis: CT and MRI findings." Korean Journal of Radiology, vol. 24, no. 2, pp. 145–155, 2023.
[7] Keiser J, Utzinger J. "Food-borne trematodiases." Clinical Microbiology Reviews, vol. 36, no. 1, pp. 12–45, 2023.

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