During a dengue outbreak, a patient presents on day 3 of fever with myalgia and retro-orbital pain. Which laboratory combination offers the highest diagnostic sensitivity at this stage?

• A IgM antibody ELISA alone (IgM peaks by day 3)
• B Haemagglutination inhibition (HI) test for antibody titre
• C NS1 antigen ELISA PLUS RT-PCR for dengue virus RNA ✓
• D Plaque reduction neutralization test (PRNT)

Explanation

In the early febrile phase (days 1–5), dengue viraemia is highest; NS1 antigen (detectable from day 1–9) and RT-PCR have the best sensitivity during this window. IgM antibody appears after day 4–5 (primary infection) or day 3–4 (secondary infection) and peaks later, so it is less reliable on day 3. HI and PRNT are research/reference tools requiring paired sera and are not used for acute diagnosis.

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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