Investigations for Eosinophilia with Intermittent Fever in a 27-year-old Indian Male
For a 27-year-old male with intermittent fever for 6 days, eosinophilia (15%), microcytic hypochromic anemia, and normal peripheral smear, the most important investigations should include concentrated stool microscopy, strongyloides serology, and schistosomiasis serology to identify the likely parasitic cause of these symptoms. 1
Primary Diagnostic Workup
Parasitic Investigations (Highest Priority)
- Concentrated stool microscopy (multiple samples, at least 3 specimens on different days) 1
- Strongyloides serology (high yield across all regions) 1
- Stool PCR for parasites (higher sensitivity than microscopy) 1
- Schistosomiasis serology (especially if history of freshwater exposure) 1
- Filariasis testing (particularly relevant in Indian context) 2
- Perianal swab or adhesive tape test (for Enterobius) 1
Additional Blood Tests
- Complete blood count with differential (to monitor eosinophil count) 2
- Serum ferritin, iron studies (to characterize the microcytic anemia) 3, 4
- HIV testing (as recommended by guidelines for unexplained eosinophilia) 1
- Liver function tests (to assess for liver involvement) 2
- Serum tryptase (to evaluate for mast cell activation) 2
Imaging and Other Tests
- Chest X-ray (to look for pulmonary infiltrates suggesting Loeffler's syndrome or tropical pulmonary eosinophilia) 1
- Abdominal ultrasound (to assess for hepatosplenomegaly) 1
- Upper GI endoscopy with duodenal biopsy (if stool studies negative but high suspicion for hookworm) 5
Clinical Context Assessment
Travel and Exposure History
- Detailed travel history to tropical/subtropical areas
- History of freshwater exposure (lakes, rivers)
- Walking barefoot in endemic areas
- Consumption of raw or undercooked foods
- Recent medication history (drug-induced eosinophilia)
Common Parasitic Causes of Eosinophilia with Fever in India
- Strongyloidiasis - can cause intermittent fever and eosinophilia 1
- Hookworm infection - associated with microcytic anemia and eosinophilia 6
- Filariasis - can present with tropical pulmonary eosinophilia and fever 1
- Visceral larva migrans (Toxocariasis) - causes fever, eosinophilia and hepatosplenomegaly 1
- Acute schistosomiasis (Katayama syndrome) - presents with fever and marked eosinophilia 1
Diagnostic Pitfalls and Considerations
- Eosinophilia may be absent in early infection or resolve spontaneously over time 7
- Serological tests may be negative in early infection (4-12 weeks needed for seroconversion) 2
- Multiple stool samples increase diagnostic yield for parasites 1
- Microcytic hypochromic anemia suggests iron deficiency, possibly from chronic blood loss due to hookworm infection 3, 6
- Normal peripheral smear does not rule out parasitic infection as cause of eosinophilia 7
- Consider empiric treatment if high clinical suspicion despite negative initial workup 1
Follow-up Testing
- Repeat stool examinations if initial tests are negative but clinical suspicion remains high
- Monitor eosinophil count every 1-3 months during and after treatment 2
- Follow-up iron studies to assess response to treatment if iron deficiency is confirmed
- Consider bone marrow examination if eosinophilia persists despite negative workup and treatment 2