What to do for a 2-year-old child with eosinophilia (high eosinophil count) and reactive lymphocytes on a blood smear?

Management of Eosinophilia in a 2-Year-Old Child

A 2-year-old child with eosinophilia (0.63 × 10^9/L) and reactive lymphocytes on blood smear requires a thorough evaluation for parasitic infections, allergic disorders, and other potential causes, with appropriate testing and possible empiric treatment based on clinical presentation.

Initial Assessment

Classification of Eosinophilia

• This child has mild eosinophilia (0.5-1.5 × 10^9/L) 1
• Reactive lymphocytes suggest an ongoing immune response, possibly viral or parasitic

Key Diagnostic Considerations

• Parasitic infections: Most common cause of eosinophilia in children 1, 2
• Allergic disorders: Common cause of mild eosinophilia 2
• Drug reactions: Consider any recent medication exposure 1
• Less common: Leukemia/lymphoma, vasculitis, immunodeficiency 2

Diagnostic Workup

First-line Investigations

1. Detailed history:

   • Travel history (tropical/subtropical areas)
   • Exposure to freshwater
   • Consumption of raw foods
   • Walking barefoot
   • Current and recent medications
   • Allergy history 1

2. Laboratory tests:

   • Complete blood count with differential (already done)
   • Stool microscopy (3 samples) for ova and parasites
   • Strongyloides serology (high priority)
   • Toxocara serology (common in children <5 years) 3, 1
   • Comprehensive metabolic panel with liver function tests
   • Urinalysis
   • C-reactive protein 1

Second-line Investigations (if indicated)

• Chest X-ray (if respiratory symptoms)
• Specific parasite serologies based on travel history
• IgE levels (if allergic etiology suspected)
• Bone marrow examination (only if hematologic malignancy suspected) 1, 4

Management Approach

For Parasitic Causes

• If travel history or exposure suggests parasitic infection, consider empiric treatment:

  • Empiric treatment option: Single dose ivermectin 200 μg/kg and albendazole 400 mg 3

• For specific parasites:

  • Strongyloidiasis: Ivermectin 200 μg/kg/day for 1-2 days 1
  • Toxocariasis (VLM): Albendazole 400mg twice daily for 5 days 3
  • Hookworm: Albendazole 400 mg daily for 3 days 1

For Allergic Causes

• Identify and eliminate allergen exposure
• Consider referral to pediatric allergist if allergic cause suspected 1, 2

For Drug-Induced Eosinophilia

• Immediate withdrawal of suspected causative medication 1

Follow-up and Monitoring

• Regular monitoring of eosinophil counts to confirm resolution 1
• Repeat complete blood count in 2-4 weeks after treatment
• If eosinophilia persists, consider more extensive evaluation including:
  • Referral to pediatric hematology
  • Assessment for end-organ damage 1, 4

Special Considerations

• Eosinophilia in children often presents with non-specific symptoms that vary with age 3
• Younger children (<6 years) more likely to present with feeding difficulties, failure to thrive, or vomiting 3
• Delayed treatment of persistent hypereosinophilia can lead to irreversible organ damage 1

When to Refer

• If eosinophilia persists after initial treatment
• If organ involvement is suspected
• If eosinophil count is >1.5 × 10^9/L on repeated testing
• If diagnosis remains unclear after initial workup 1, 4

Common Pitfalls

• Failing to obtain adequate stool samples (minimum 3)
• Missing parasitic infections in children with mild eosinophilia
• Not considering Strongyloides infection, which can cause hyperinfection with immunosuppression 3, 1
• Premature use of corticosteroids before ruling out parasitic infections, particularly strongyloidiasis 3