What is the appropriate management for a patient presenting with acute peripheral eosinophilia?

Management of Acute Peripheral Eosinophilia

For acute peripheral eosinophilia, immediately assess for end-organ damage (cardiac, pulmonary, neurologic) and obtain a detailed travel/exposure history, as helminth infections account for 19-80% of cases in returning travelers and require urgent empiric treatment, while any evidence of organ involvement demands emergency corticosteroid therapy. 1

Immediate Risk Stratification

Any patient with eosinophilia presenting with chest pain, dyspnea, heart failure symptoms, altered mental status, focal neurological deficits, or persistent respiratory symptoms requires urgent medical evaluation for end-organ damage. 1 These presentations carry significant mortality risk and necessitate immediate intervention before diagnostic workup is complete.

Critical Red Flags Requiring Emergency Assessment:

• Cardiac involvement (chest pain, dyspnea, arrhythmias, heart failure) - obtain ECG, cardiac troponin, NT-proBNP, and echocardiography immediately 1
• Pulmonary involvement (persistent cough, wheezing, infiltrates on imaging) - perform chest X-ray and pulmonary function tests urgently 1
• Neurological involvement (altered mental status, focal deficits, peripheral neuropathy) - consider EMG and nerve biopsy 1
• Absolute eosinophil count ≥5.0 × 10⁹/L at any time carries high risk regardless of symptoms 1

Severity-Based Management Algorithm

Mild Eosinophilia (0.5-1.5 × 10⁹/L):

In non-endemic areas, allergic disorders and medications are the most common causes, but in returning travelers or migrants, helminth infections account for 19-80% of cases and must be excluded first. 1, 2

Diagnostic approach:

• Obtain detailed travel history focusing on fresh water exposure in Africa/tropical regions, raw/undercooked meat consumption, and timing relative to eosinophilia onset 1, 2
• Send three separate concentrated stool specimens for ova and parasites 1
• Order Strongyloides serology and culture immediately 1
• Add Schistosomiasis serology if fresh water exposure in endemic areas 1

Treatment for returning travelers with asymptomatic mild eosinophilia:

• Empiric treatment with albendazole 400 mg single dose PLUS ivermectin 200 μg/kg single dose 2, 3
• For confirmed Strongyloidiasis: ivermectin 200 μg/kg daily for 2 days 1, 2

Moderate to Severe Eosinophilia (≥1.5 × 10⁹/L):

If persisting >3 months after infectious causes excluded or treated, refer to hematology for evaluation of primary eosinophilic disorders. 1

Before initiating any corticosteroid therapy, you must exclude Strongyloides infection, as immunosuppression can trigger fatal hyperinfection syndrome. 1 This is a critical pitfall that kills patients.

Specific Clinical Presentations

Gastrointestinal Symptoms (Dysphagia, Food Impaction):

Perform upper endoscopy with multiple biopsies (minimum 6 biopsies: 2-3 from proximal and 2-3 from distal esophagus) to evaluate for eosinophilic esophagitis. 1, 2 Note that peripheral eosinophilia occurs in only 10-50% of adults with eosinophilic esophagitis, so normal blood counts do not exclude the diagnosis. 4, 1

Treatment for confirmed eosinophilic esophagitis:

• First-line: topical swallowed corticosteroids (fluticasone or budesonide), which decrease blood eosinophil counts in 88% of patients 1, 2
• Histological remission defined as <15 eosinophils per 0.3 mm² 1, 3
• Maintenance therapy is mandatory after achieving remission due to high clinical relapse rates 1

Pulmonary Symptoms (Cough, Wheezing, Infiltrates):

For tropical pulmonary eosinophilia (typically eosinophil count >3 × 10⁹/L), initiate diethylcarbamazine (DEC) promptly to prevent irreversible pulmonary fibrosis, but FIRST exclude Loa loa co-infection. 1

Critical warning: Do not use DEC if microfilariae are seen on blood film, as it may cause fatal encephalopathy with Loa loa. Instead, use corticosteroids with albendazole first to reduce microfilarial load to <1000/ml before definitive treatment. 1

Treatment protocol:

• DEC for tropical pulmonary eosinophilia (after excluding Loa loa) 1
• Adjunctive prednisolone 20 mg/day for 5 days initially for ongoing alveolitis 1
• 20% of patients relapse and require re-treatment with second DEC course 1

For Loeffler's syndrome (Ascaris, hookworm):

• Albendazole 400 mg twice daily for 3 days 1

For Schistosomiasis with pulmonary involvement:

• Praziquantel 40 mg/kg as single dose, repeated at 6-8 weeks 1
• Add prednisolone 20 mg/day for 5 days in acute Katayama syndrome 1

Neurological Symptoms:

For eosinophilic meningitis, corticosteroids are the mainstay of treatment (prednisolone 60 mg daily for 14 days). 4 Consider Angiostrongylus cantonensis in patients with travel to SE Asia, Caribbean, or Hawaii presenting with severe headache, meningism, and visual disturbances. 4

For schistosomiasis with CNS involvement (myelitis, paraplegia):

• Praziquantel 40 mg/kg twice daily for 5 days 4
• Dexamethasone 4 mg four times daily, reducing after 7 days, over total of 2-6 weeks 4
• Treat with corticosteroids alone initially in acute neuroschistosomiasis to avoid neurological complications 4

Common Pitfalls to Avoid

Do not assume eosinophilia alone is adequate screening for helminth infection - many infected patients have normal eosinophil counts, and only tissue-invasive helminths cause eosinophilia. 1, 5

Do not wait for symptoms to develop before investigating persistent moderate-to-severe eosinophilia - end-organ damage can be subclinical initially and progress to irreversible fibrosis. 1

Do not rely solely on peripheral eosinophil counts to assess tissue eosinophilia in conditions like eosinophilic esophagitis - tissue biopsy is the gold standard. 4, 1

Do not start corticosteroids before excluding Strongyloides in any patient with potential exposure - this can trigger fatal hyperinfection syndrome. 1

Do not use DEC if Loa loa microfilariae are present on blood film - this causes fatal encephalopathy. 1

Follow-Up Monitoring

• Repeat eosinophil counts after treatment to assess response 2, 3
• For eosinophilic esophagitis: if symptoms recur during treatment, repeat endoscopy with biopsies 1, 2
• Monitor for corticosteroid side effects (bone mineral density, adrenal suppression) 2
• For treated helminth infections: repeat stool studies or serology as appropriate for specific parasite life cycles 4