A 26-year-old woman in Kerala presents with high-grade fever of 3 days duration during a dengue outbreak. Which laboratory test is most likely to be positive at this stage of illness?
- A IgM capture ELISA for dengue
- B IgG ELISA for dengue
- C NS1 antigen detection ✓
- D Peripheral smear showing schizonts
Correct answer: C. NS1 antigen detection
Explanation
NS1 antigen appears in serum from day 1 of fever and remains detectable up to about day 5, making it the test of choice in the first 5 days of illness. Dengue-specific IgM becomes detectable only from approximately day 5 onward and peaks in the second week, so it would likely be negative on day 3. IgG rises even later or indicates past infection. A peripheral smear for malarial parasites addresses a different diagnosis entirely.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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