What is the diagnosis and management for a male patient with left arm and leg paresthesias after physical activity, presenting with neutropenia (low neutrophil count) and eosinophilia (high eosinophil count)?

Diagnosis and Management of Paresthesias with Neutropenia and Eosinophilia Post-Exercise

Primary Diagnosis: Parasitic Infection with Neurological Involvement

This patient requires urgent evaluation for helminthic parasitic infection causing neurological manifestations, specifically neuroschistosomiasis or Angiostrongylus cantonensis (rat lungworm), given the combination of focal neurological symptoms (left arm and leg paresthesias) and eosinophilia following physical activity. 1

The constellation of unilateral paresthesias with eosinophilia (9.3%, absolute 0.26) in a patient with recent physical exertion strongly suggests parasitic CNS involvement rather than a primary hematologic disorder. 1

Immediate Diagnostic Workup

Critical History Elements

• Travel history: Detailed questioning about fresh water exposure in Africa, South/Southeast Asia, Central/South America, Caribbean, or Hawaii within the past 1-3 years 1, 2
• Dietary exposures: Consumption of undercooked snails, prawns, crabs, frogs, or raw/undercooked pork 1
• Timing: Incubation for Angiostrongylus is 1 day to 3 months; neurocysticercosis >1 year; schistosomiasis can be chronic 1

Urgent Neurological Assessment

• Brain and spinal cord MRI with contrast: Essential to identify CNS lesions, cord enlargement, or contrast enhancement suggestive of parasitic involvement 1
• Lumbar puncture with CSF analysis: Look for CSF eosinophilia (present in 20% of neurocysticercosis, common in Angiostrongylus), lymphocytosis, and elevated protein 1
• Serology: Angiostrongylus serology (available through specialized tropical disease centers), Schistosoma serology, Taenia solium serology 1

Parasitic Workup

• Stool microscopy: Three separate concentrated specimens for ova and parasites 2, 3
• Strongyloides serology and culture: Critical given risk of fatal hyperinfection if immunosuppressed 2, 4
• Peripheral blood smear: Exclude Loa loa microfilariae before treatment (fatal encephalopathy risk with diethylcarbamazine) 2

Cardiac and End-Organ Assessment

• ECG, troponin, NT-proBNP: Screen for eosinophil-mediated cardiac damage, as eosinophilia ≥1.5 × 10⁹/L carries risk of endomyocardial involvement 2, 4
• Echocardiogram: If troponin elevated or cardiac symptoms present 2

Differential Diagnosis Considerations

Neutropenia Context

The mild neutropenia (ANC 1.31) is likely secondary to viral infection or early parasitic infection rather than a primary bone marrow disorder, given the patient's age and acute presentation. 5 Post-viral neutropenia can persist for weeks following asymptomatic infections. 5 However, this does not change the urgency of parasitic evaluation given the neurological symptoms.

Eosinophilia Significance

• Absolute eosinophil count 0.26 (9.3%) represents mild eosinophilia that warrants full parasitic investigation given neurological symptoms 2
• Helminth infections account for 19-80% of eosinophilia in travelers, but normal eosinophil counts do not exclude parasitic infection 2, 4
• Only tissue-invasive helminths cause peripheral eosinophilia 2

Treatment Algorithm

If Angiostrongylus cantonensis Confirmed or Highly Suspected

• Prednisolone 60 mg daily for 14 days: Mainstay of treatment, reduces severity and duration of headache and neurological symptoms 1
• Albendazole 15 mg/kg/day for 14 days: Likely provides additional benefit 1
• Therapeutic lumbar punctures: May be necessary for symptom relief 1

If Neurocysticercosis (Cysticercal Meningitis) Suspected

• Corticosteroids FIRST: Dexamethasone 4-12 mg/day, reducing after 7 days 1
• Albendazole 400 mg twice daily for 14 days: After corticosteroid initiation 1
• Ventricular shunting: If hydrocephalus develops 1
• Repeated courses: May be required 1

If Neuroschistosomiasis Suspected

• Dexamethasone 4 mg four times daily: Initiate BEFORE antiparasitic therapy, reduce over 2-6 weeks 1
• Praziquantel 40 mg/kg twice daily for 5 days: Start after corticosteroid loading 1
• Critical warning: In acute Katayama syndrome with neurological symptoms, treat with corticosteroids ALONE initially to avoid neurological complications 1

Empiric Treatment if Testing Delayed

• Albendazole 400 mg single dose PLUS ivermectin 200 μg/kg single dose: Covers most helminth infections in returning travelers with negative initial testing 2, 3
• Do NOT use empiric treatment if Loa loa possible (West/Central Africa travel with subcutaneous swellings or eye worm) without excluding microfilaremia first 2

Critical Pitfalls to Avoid

• Never delay neuroimaging: Parasitic CNS involvement can progress rapidly to permanent neurological damage or death 1, 4
• Never assume normal eosinophil count excludes helminth infection: Many infected patients have normal counts 2, 4
• Never use diethylcarbamazine if Loa loa possible: Check blood smear first; if microfilariae present, use corticosteroids with albendazole to reduce load to <1000/mL before definitive treatment 2
• Never start antiparasitic therapy before corticosteroids in neuroschistosomiasis: This can precipitate severe inflammatory reactions 1
• Never attribute eosinophilia solely to allergies without excluding parasites: Especially with neurological symptoms 2, 4

Hematology Referral Indications

• If eosinophilia persists >3 months after parasitic treatment or exclusion 2, 3
• If absolute eosinophil count >5.0 × 10⁹/L at any time 2
• If neutropenia worsens or persists beyond 3 months without clear etiology 5, 6

Prognosis Considerations

• Angiostrongylus: Generally good with corticosteroid treatment 1
• Neurocysticercosis with meningitis: Poor prognosis, particularly with acute hydrocephalus 1
• Neuroschistosomiasis: Variable; early treatment improves outcomes 1