What is the treatment for eosinophilia?

Treatment of Eosinophilia

The treatment of eosinophilia should be directed at the underlying cause, with empirical treatment using albendazole 400 mg plus ivermectin 200 μg/kg as a single dose for asymptomatic eosinophilia in returning travelers or migrants when parasitic infection is suspected. 1, 2

Diagnostic Approach

Before initiating treatment, it's essential to determine the cause of eosinophilia:

1. Define severity of eosinophilia:

   • Mild: >0.5 × 10⁹/L
   • Moderate: >1.5 × 10⁹/L
   • Severe: >5.0 × 10⁹/L 2

2. Initial evaluation:

   • Detailed travel history (tropical/subtropical areas, freshwater exposure)
   • Medication history (drug-induced eosinophilia)
   • Allergy history
   • Consumption of raw foods
   • Walking barefoot in endemic areas 2

3. Laboratory testing:

   • Complete blood count with differential
   • Concentrated stool microscopy (3 samples)
   • Strongyloides serology
   • Schistosomiasis serology (if relevant travel history)
   • Peripheral blood smear
   • Liver function tests 1, 2

Treatment Algorithm

1. Parasitic Causes (Common in Travelers/Migrants)

• Asymptomatic eosinophilia with negative stool microscopy:

  • Empirical treatment with albendazole 400 mg (single dose) PLUS ivermectin 200 μg/kg (single dose) 1
  • Important: Exclude Loa loa in people who have traveled to endemic regions BEFORE treating with ivermectin 1

• Specific parasitic infections:

  • Hookworm: Albendazole 400 mg daily for 3 days 2
  • Schistosomiasis: Praziquantel 40 mg/kg twice daily for 5 days 2
  • Strongyloidiasis: Ivermectin 200 μg/kg/day for 1-2 days 2
  • Acute schistosomiasis (Katayama syndrome): Praziquantel plus corticosteroids; repeat praziquantel at 8 weeks 1
  • Neurocysticercosis: Albendazole 400 mg twice daily for 14 days with dexamethasone (4-12 mg/day, reducing after 7 days) 1
  • Angiostrongylus cantonensis: Prednisolone 60 mg daily for 14 days; consider albendazole (15 mg/kg/day for 14 days) 1

2. Non-Parasitic Causes

• Drug-induced eosinophilia:

  • Immediate withdrawal of the causative medication 2

• Eosinophilic esophagitis:

  • Treatment options should be discussed with patients
  • Regular monitoring with clinic visits to assess symptoms and compliance 1
  • Consider endoscopic monitoring in children until a treatment regimen controls symptoms 1

• Hypereosinophilic syndrome:

  • Corticosteroids are first-line therapy 3
  • Consider hydroxyurea and interferon-α for steroid-refractory cases 3
  • Mepolizumab (IL-5 antagonist) for idiopathic hypereosinophilic syndrome 3

• Clonal eosinophilia with PDGFRA or PDGFRB rearrangements:

  • Imatinib (highly effective) 3

Monitoring and Follow-up

• Regular clinic visits to assess symptoms, compliance with therapy, and adverse effects 1
• Follow-up complete blood counts to confirm resolution of eosinophilia 2
• For persistent eosinophilia, monitor for end-organ damage (cardiac, pulmonary, neurological) 2
• In children with eosinophilic esophagitis, consider periodic endoscopy to evaluate for persistent esophageal eosinophilia 1

Important Caveats

• Persistent eosinophilia (>1.5 × 10⁹/L for >3 months) can cause significant organ damage, particularly endomyocardial fibrosis and thromboembolic complications 2, 3
• When treating with ivermectin, always exclude Loa loa infection first to prevent severe adverse reactions 1
• For neurocysticercosis, hydrocephalus may require ventricular shunting 1
• For schistosomiasis, eggs and immature schistosomulae are relatively resistant to treatment; repeat treatment at 8 weeks 1
• Therapeutic lumbar punctures may be necessary for Angiostrongylus cantonensis 1

By systematically identifying the underlying cause and applying the appropriate treatment, most cases of eosinophilia can be effectively managed to prevent long-term complications and improve patient outcomes.