How do you manage a patient with eosinophilia of 900?

Management of Eosinophil Count of 900/μL

An eosinophil count of 900/μL (0.9 × 10⁹/L) represents mild eosinophilia that requires systematic evaluation for underlying causes but does not automatically require treatment—management depends entirely on identifying the etiology through targeted history, examination for end-organ involvement, and appropriate testing. 1

Initial Risk Stratification

• Mild eosinophilia (0.5-1.5 × 10⁹/L) most commonly results from allergic disorders or medications in non-endemic areas, but helminth infections account for 19-80% of cases in returning travelers or migrants 1
• At this level without symptoms or signs of organ involvement, a watch-and-wait approach with close follow-up is appropriate while completing diagnostic evaluation 2, 3
• Urgent evaluation is NOT required unless the patient presents with symptoms suggesting end-organ damage (chest pain, dyspnea, heart failure symptoms, altered mental status, focal neurological deficits, or persistent respiratory symptoms) 1

Essential Diagnostic Evaluation

Travel and Exposure History

• Obtain detailed travel history focusing on fresh water exposure in Africa/tropical regions, raw/undercooked meat consumption, and timing of travel relative to eosinophilia onset 1
• Helminth infections must be excluded first, as they represent the most common identifiable cause in exposed populations 4, 1

Symptom-Directed Assessment

• For gastrointestinal symptoms (dysphagia, food impaction, abdominal pain): Consider eosinophilic esophagitis, though peripheral eosinophilia occurs in only 10-50% of adults with this condition—endoscopy with multiple biopsies (minimum 6 biopsies from at least 2 different esophageal sites) is required for diagnosis 4, 5
• For respiratory symptoms (cough, wheezing, dyspnea): Obtain chest radiograph and consider pulmonary function tests 1
• For any neurological symptoms: Urgent parasitic workup is mandatory, particularly for Strongyloides in immunocompromised patients due to fatal hyperinfection syndrome risk 1

First-Line Laboratory Testing

• Three separate concentrated stool specimens for ova and parasites 4, 1
• Strongyloides serology and culture (critical because this parasite can persist lifelong and cause fatal hyperinfection in immunocompromised patients) 1
• Schistosomiasis serology if fresh water exposure in endemic areas 1
• Review all medications for potential drug-induced eosinophilia 1

Treatment Approach Based on Etiology

If Travel History to Endemic Regions

• Empiric treatment with albendazole 400 mg single dose PLUS ivermectin 200 μg/kg single dose may be considered for returning travelers with asymptomatic eosinophilia 5, 6
• For confirmed Strongyloidiasis: Ivermectin 200 μg/kg daily for 2 days 1, 6
• For Schistosomiasis: Praziquantel 40 mg/kg as single dose, repeated at 6-8 weeks 1, 6

If Eosinophilic Esophagitis Confirmed

• First-line treatment is topical swallowed corticosteroids (fluticasone or budesonide), which decrease blood eosinophil counts in 88% of patients 5, 1
• Maintenance therapy is mandatory after achieving remission due to high clinical relapse rates 1
• Histological remission is defined as <15 eosinophils per 0.3 mm² 4, 5

If Allergic/Atopic Disease

• Optimize treatment for underlying allergic conditions (allergic rhinitis, atopic dermatitis, asthma) 5
• Consider joint management with allergist for refractory cases or significant concomitant atopic disease 4, 5

When to Escalate Care

• Refer to hematology if eosinophilia ≥1.5 × 10⁹/L persists for more than 3 months after infectious causes have been excluded or treated 1
• This threshold is critical because persistent moderate-to-severe eosinophilia carries significant risk of end-organ damage and may represent primary hematologic disorders requiring specialized evaluation 1, 2

Critical Pitfalls to Avoid

• Do not assume normal eosinophil counts exclude parasitic infection—many helminth-infected patients have normal eosinophil counts, and only tissue-invasive parasites cause eosinophilia 1
• Do not rely solely on peripheral eosinophil counts to diagnose eosinophilic esophagitis—tissue biopsy remains the gold standard 5, 1
• Do not use diethylcarbamazine if Loa loa microfilariae are present on blood film, as this may cause fatal encephalopathy—use corticosteroids with albendazole first to reduce microfilarial load 1
• In immunocompromised patients with any eosinophilia and potential helminth exposure, urgent evaluation for Strongyloides is mandatory due to high mortality risk of hyperinfection syndrome 1

Follow-Up Monitoring

• Repeat eosinophil counts after treatment to assess response 5
• If symptoms recur while on treatment for eosinophilic esophagitis, repeat endoscopy with biopsies 4, 5
• For patients on corticosteroids, monitor for side effects including bone mineral density and adrenal suppression, particularly in children and adolescents 4