Parasitic Liver Infections in Pediatrics

Parasitic infections of the liver, though less common than bacterial or viral causes, carry significant morbidity when they occur. Early recognition, targeted diagnostics, and prompt therapy are essential to prevent complications.

A. Amebic Liver Abscess

1. Etiology & Transmission

• Caused by the protozoan Entamoeba histolytica

• Infection via ingestion of mature cysts in contaminated food or water (fecal–oral route)

2. Pathogenesis

• Trophozoites excyst in the colon → invade mucosa → enter portal circulation → seed the liver

• Abscesses most often develop in the right lobe due to higher portal flow

3. Clinical Presentation

• Fever and drenching night sweats

• RUQ or epigastric pain; tender hepatomegaly

• History of dysentery or asymptomatic colonic infection with “flask-shaped” ulcers

4. Laboratory Findings

• Marked leukocytosis with left shift

• Elevated ESR/CRP

• Mild–moderate ↑ AST/ALT; ↑ alkaline phosphatase and GGT; bilirubin usually normal

5. Imaging

• Ultrasound: cystic lesion with low-level internal echoes

• CT: round, hypodense lesion; peripheral rim enhancement

6. Diagnosis

• Serology (indirect hemagglutination or ELISA) positive in ~95% of hepatic cases

• Stool exam for trophozoites or cysts: positive in <50% of liver-only disease

7. Drainage

• “Anchovy-paste” aspirate—sterile, brownish fluid

• Only drain if:

  • Risk of rupture (size >10 cm or left lobe)

  • No clinical improvement after 72 hours of therapy

8. Treatment

1. Tissue amebicide

   • Metronidazole 10 mg/kg/dose three times daily (maximum 750 mg/dose) × 10–14 days

2. Luminal amebicide (to eradicate colonic carriage)

   • Paromomycin 25–35 mg/kg/day in three divided doses × 7 days

3. Follow-up ultrasound at 4–6 weeks to confirm resolution

B. Echinococcal (Hydatid) Disease

1. Etiology & Transmission

• Caused by the tapeworm Echinococcus granulosus

• Humans are accidental intermediate hosts; infection via ingestion of eggs shed in dog or livestock feces

2. Pathogenesis

• Embryos (oncospheres) penetrate intestinal wall → portal circulation → hepatic cysts

• Cysts grow slowly, forming a laminated outer layer and inner germinal layer with “daughter” cysts

3. Clinical Presentation

• Often silent until cysts reach 5–10 cm

• RUQ discomfort or palpable mass

• Complications:

  • Pressure on hepatic veins → Budd–Chiari–like syndrome

  • Cyst rupture → anaphylaxis, peritoneal seeding

4. Laboratory Findings

• Eosinophilia in 20–30%

• Mild ↑ AST/ALT

5. Imaging

• Ultrasound: “snowflake” — hydatid sand, septations, daughter cysts

• CT/MRI: superb delineation of cyst wall, internal membranes, calcifications

6. Diagnosis

• Serology: ELISA or indirect hemagglutination positive in 80–90%

• Avoid fine-needle aspiration except under controlled conditions due to risk of spillage

7. Treatment

1. Medical therapy

   • Albendazole 10–15 mg/kg/day in two divided doses (maximum 800 mg/day) × 3–6 months

   • Monitor liver enzymes monthly

2. PAIR procedure (percutaneous aspiration, injection, reaspiration)

   • Puncture under ultrasound/CT guidance → inject hypertonic saline or ethanol → reaspirate

3. Surgical removal

   • Indications: large cysts (>10 cm), superficial location, biliary communication, or PAIR failure

4. Follow-up

   • Imaging every 6 months for 2 years to detect recurrence

C. Ascariasis

1. Etiology & Transmission

• Caused by the roundworm Ascaris lumbricoides

• Infection via ingestion of eggs in contaminated soil or food

2. Pathogenesis

• Larvae hatch in intestine → migrate via bloodstream to lungs → ascend tracheobronchial tree → swallowed → mature in intestine

• Adult worms may migrate into the ampulla of Vater, lodging in bile ducts and gallbladder

3. Clinical & Hepatic Manifestations

• Often asymptomatic or abdominal discomfort

• Hepatobiliary: biliary colic, cholangitis, biliary obstruction, hepatic granulomas

4. Diagnosis

• Stool ova and parasite exam

• Ultrasound/CT: tubular echogenic structures within bile ducts

5. Treatment

• Pyrantel pamoate 11 mg/kg PO once (max 1 g)

• Alternative: albendazole 400 mg PO once

D. Malaria

1. Etiology & Transmission

• Plasmodium species (falciparum, vivax, malariae, ovale) via infected Anopheles mosquito

2. Pathogenesis

• Sporozoites invade hepatocytes → exoerythrocytic schizogony → merozoites released → infect RBCs

3. Clinical Presentation

• High-spiking fevers with chills/rigors; headache, myalgia, nausea, vomiting, diarrhea

• Hepatomegaly and moderate jaundice (hemolysis + hepatic dysfunction)

4. Laboratory Findings

• Hemolytic anemia, thrombocytopenia

• ↑ AST/ALT; indirect hyperbilirubinemia

5. Diagnosis

• Thick and thin peripheral blood smears (gold standard)

• Rapid diagnostic tests (HRP2 or pLDH antigen detection)

6. Histopathology (if biopsy ever performed)

• Kupffer cell hyperplasia with malarial pigment

• Sinusoidal congestion

7. Treatment

• Uncomplicated P. falciparum or P. vivax: Artemisinin-based combination therapy (ACT)

  • Artemether-lumefantrine for children ≥5 kg

• Severe malaria: IV artesunate until able to tolerate oral therapy, then complete with ACT

• P. vivax/ovale: add primaquine (0.25 mg/kg/day × 14 days) for hypnozoite eradication; G6PD testing required

Key Points & Prevention

• Amebic and hydatid abscesses require specific antiparasitic therapy; drainage is reserved for complications.

• Ascariasis and malaria have oral pharmacotherapies that differ by species and severity.

• Always confirm E. histolytica, Echinococcus, Ascaris, or Plasmodium by laboratory or imaging before initiating targeted treatment.

• Improve sanitation, provide safe drinking water, and implement vector control to prevent these infections.

• In endemic areas, screen high-risk children (immigrants, travelers, immunocompromised) to enable early diagnosis and management.