Treatment of Eosinophilia
For patients with asymptomatic eosinophilia, empirical treatment with albendazole 400 mg single dose plus ivermectin 200 μg/kg single dose is recommended as first-line therapy. 1
Diagnostic Approach Before Treatment
- Evaluate for common causes of eosinophilia, including parasitic infections, especially in those with travel history 1, 2
- Perform stool microscopy and serology for specific helminth infections based on travel history 2, 3
- Consider endoscopy with multiple biopsies for patients with gastrointestinal symptoms to evaluate for eosinophilic esophagitis 2
- For persistent eosinophilia ≥ 1.5 × 10⁹/L for more than 3 months without evidence of organ damage, refer to a hematologist 1
Treatment Algorithm Based on Cause
Parasitic Infections
- For asymptomatic eosinophilia in patients aged > 24 months: albendazole 400 mg single dose plus ivermectin 200 μg/kg single dose 1
- For strongyloidiasis: ivermectin 200 μg/kg daily for 2 days 3
- For schistosomiasis: praziquantel 40 mg/kg in two divided doses for 1 day 3
- For onchocerciasis: diethylcarbamazine (seek specialist advice due to potential adverse reactions) 1
Eosinophilic Esophagitis
- Proton pump inhibitor therapy twice daily for 8-12 weeks 3
- Topical steroids for inducing histological and clinical remission 3
- Two-food elimination diet (milk +/- wheat or egg) for 8-12 weeks with dietitian support 2, 3
Hypereosinophilic Syndrome
- For milder forms of eosinophilia (<1.5 × 10⁹/L) without organ involvement: watch and wait approach with close follow-up 4
- First-line therapy: corticosteroids 4
- Second-line options: hydroxyurea and interferon-alpha for steroid-refractory cases 4
- For PDGFRA or PDGFRB rearrangements: imatinib (critical to identify these cases due to excellent response) 4
- For FGFR1-rearranged neoplasms: pemigatinib for relapsed or refractory cases 4
- FDA-approved for idiopathic hypereosinophilic syndrome: mepolizumab (anti-IL-5 antibody) 4
Management of Complications
Neurological Involvement
- For eosinophilic meningitis: corticosteroids plus albendazole 1
- For neuroschistosomiasis: praziquantel 40 mg/kg twice daily for 5 days plus dexamethasone 4 mg four times daily, reducing after 7 days over 2-6 weeks 1
- For toxocariasis with neurological involvement: corticosteroids plus albendazole 1
End-Organ Damage
- Any patient presenting with evidence of end-organ damage needs urgent medical assessment and consideration of emergency treatment 1
- For cardiac, pulmonary, or central nervous system involvement: immediate specialist referral 1
Monitoring Response
- Follow-up eosinophil counts should be obtained after treatment to assess response 2
- For eosinophilic esophagitis, histological remission is defined as <15 eosinophils per 0.3 mm² in tissue biopsies 2
- For persistent eosinophilia despite treatment, consider referral to a hematologist for further investigation 1
Important Considerations
- Persistent eosinophilia of any degree, especially at very high levels, can cause significant end-organ damage, particularly affecting the heart, lungs, and central nervous system 1
- Many people with helminth infection do not have eosinophilia, so testing for eosinophilia alone is not an adequate screening strategy for helminth infection 1
- In some cases of persistent eosinophilia, no cause can be identified - termed idiopathic hypereosinophilia 1
- For patients with refractory eosinophilia and/or significant concomitant atopic disease, consider joint management by appropriate specialists 2