What are the next steps in managing a patient with a differential count showing eosinophilia (Eosinophils 13 percent) and a total leukocyte count (TLC) of 5400, with stable vitals and no other complaints?

Management of Eosinophilia (13%) with Stable Vitals

For a patient with eosinophilia (13%) and stable vitals with no other complaints, a comprehensive evaluation for underlying causes is necessary, with particular focus on helminth infections which are the most common identifiable cause of eosinophilia in returning travelers and migrants.

Initial Assessment

• Calculate the absolute eosinophil count (AEC) by multiplying the percentage of eosinophils (13%) by the total leukocyte count (5400): 13% × 5400 = 702 cells/μL 1
• This represents mild eosinophilia (defined as 500-1500 cells/μL) 2
• Note the relative lymphocytosis (53%) and relative neutropenia (33%), which may provide additional diagnostic clues 1

Key Diagnostic Considerations

Travel and Migration History

• Obtain detailed travel history, as helminth infections are the most common identifiable cause of eosinophilia in returning travelers (diagnosis rates 19-80%) 3
• Ask specifically about travel to areas with endemic helminth infections 3
• For travelers to West Africa, specific filarial investigations should be considered 3

Medication Review

• Review all medications as drugs are among the most common non-infectious causes of eosinophilia in countries with low rates of endemic helminth infections 3
• Common culprits include NSAIDs, beta-lactam antibiotics, and nitrofurantoin 3

Allergy and Atopy Assessment

• Evaluate for allergic conditions (asthma, eczema, hay fever) which are common causes of mild eosinophilia 3, 1
• However, mild allergic conditions alone rarely cause eosinophil counts >1500 cells/μL 1

Recommended Investigations

First-Line Tests

• Complete blood count with manual differential to confirm eosinophilia 1
• Stool examination for ova and parasites (three samples on different days) 3
• Serological tests for common helminth infections based on travel history 3
• Basic metabolic panel and liver function tests to assess for end-organ involvement 4

Additional Tests Based on Clinical Context

• If travel history to endemic areas: specific serological tests for schistosomiasis, strongyloidiasis, and filariasis 3
• If respiratory symptoms are present or develop: consider chest imaging and evaluation for allergic bronchopulmonary aspergillosis (ABPA), especially with history of asthma 3
• If persistent eosinophilia (≥1.5 × 10⁹/L for >3 months): consider hematology referral for bone marrow examination and genetic testing to rule out primary eosinophilic disorders 3, 4

Management Approach

For Mild Eosinophilia (500-1500 cells/μL)

• If travel history to endemic areas and no other obvious cause: consider empirical treatment with albendazole 400 mg single dose plus ivermectin 200 μg/kg single dose (for patients >24 months of age) 3
• For specific helminth infections identified, use targeted therapy (e.g., albendazole 400 mg single dose for hookworm) 3

Monitoring

• Follow-up complete blood count in 4-6 weeks to assess response to treatment 4
• If eosinophilia persists despite treatment, consider referral to specialist for further evaluation 3
• Monitor for development of end-organ damage, particularly affecting heart, lungs, and central nervous system 3

Important Considerations

• Even mild persistent eosinophilia can cause end-organ damage if left untreated 3
• Some helminth infections (e.g., Strongyloides stercoralis) can persist lifelong and later present as hyperinfection syndrome with high mortality in immunocompromised patients 3
• Testing for eosinophilia alone is not an adequate screening strategy for helminth infection, as many people with helminth infections do not have eosinophilia 3
• If no cause is identified and eosinophilia persists, consider idiopathic hypereosinophilia 3, 4