Management of Eosinophilia
The management of eosinophilia should begin with identifying the underlying cause, with helminth infections being the most common identifiable cause in returning travelers and migrants, followed by empiric treatment with albendazole plus ivermectin for those with asymptomatic eosinophilia. 1
Definition and Clinical Significance
Eosinophilia is defined as a peripheral blood eosinophil count > 0.5 × 10⁹/L. The patient's current value is 0.73 × 10³/μL (or 0.73 × 10⁹/L), which exceeds this threshold.
Persistent eosinophilia, especially at high levels, can cause significant end-organ damage, particularly affecting:
- Heart
- Lungs
- Central nervous system 1
Diagnostic Approach
Step 1: Rule Out Common Non-Infectious Causes
- Allergies and atopy (asthma, eczema, hay fever)
- Drug reactions
- Autoimmune disorders
- Malignancies (lymphomas, myeloid neoplasms) 1
Step 2: Evaluate for Infectious Causes Based on Travel/Migration History
- Helminth infections are the most common identifiable cause in travelers/migrants
- Key investigations:
- Concentrated stool microscopy (3 samples)
- Strongyloides serology
- Schistosomiasis serology
- Filarial serology (if travel to/residence in West Africa) 1
Step 3: Assess for Organ Involvement
- Respiratory: Chest X-ray, pulmonary function tests
- Gastrointestinal: Abdominal imaging if symptoms present
- Cardiac: ECG, echocardiogram if symptoms or persistent high eosinophilia
- Neurological: Brain imaging if symptoms present 1
Treatment Algorithm
1. For Asymptomatic Eosinophilia (> 24 months of age)
First-line empirical treatment:
- Albendazole 400 mg single dose PLUS
- Ivermectin 200 μg/kg single dose 1
2. For Symptomatic Eosinophilia
Treatment depends on identified cause:
If Helminth Infection Identified:
- Strongyloidiasis: Ivermectin 200 μg/kg daily for 2 days
- Schistosomiasis: Praziquantel (dose varies by species)
- Filariasis: Treatment varies by species (may require diethylcarbamazine with caution)
- Other helminth infections: Specific treatment based on pathogen 1
If Non-Infectious Cause Identified:
- Drug reaction: Discontinue offending agent
- Allergic disorder: Treat underlying allergy
- Autoimmune disease: Immunosuppressive therapy as indicated
- Malignancy: Refer to hematology/oncology 1
3. For Persistent Unexplained Eosinophilia
- If ≥ 1.5 × 10⁹/L for more than 3 months without identified cause
- Refer to hematology for evaluation of hypereosinophilic syndrome or other myeloid disorders 1
Special Considerations
End-Organ Damage
- Any patient with evidence of end-organ damage needs urgent medical assessment
- Consider emergency treatment with corticosteroids (prednisolone 60 mg daily) if severe organ involvement 1, 2
Strongyloides Infection
- Critical to rule out before starting corticosteroids
- Strongyloides can cause hyperinfection syndrome with high mortality in immunocompromised patients 1
Monitoring
- Follow-up eosinophil count 4-6 weeks after treatment
- If eosinophilia persists despite empiric treatment, consider:
Pitfalls to Avoid
Don't miss Strongyloides infection before starting immunosuppression - can lead to fatal hyperinfection syndrome 1
Don't rely solely on eosinophil count to screen for helminth infections - many infected patients have normal counts 1
Don't forget non-infectious causes - allergies, drugs, and autoimmune conditions are common causes in non-endemic areas 1
Don't delay treatment in patients with evidence of organ damage - this can lead to irreversible complications 1
Don't overlook the need for specialist referral for persistent unexplained eosinophilia 1