During a dengue outbreak, NS1 antigen is positive on Day 2 of fever. On Day 8, the appropriate diagnostic test to confirm dengue is:

• A NS1 antigen test
• B Dengue RNA PCR
• C Platelet aggregation assay
• D IgM antibody ELISA (MAC-ELISA) ✓

Explanation

Dengue diagnostics depend on the phase of illness. NS1 antigen and PCR are positive during the febrile/viraemic phase (Days 1–5). IgM antibodies (MAC-ELISA) become detectable from Day 5–6 onwards and persist for 2–3 months — making IgM ELISA the test of choice after Day 5. By Day 8, the viraemia has resolved, NS1 antigen and PCR are typically negative. IgG antibody appears later and persists for years; a four-fold rise in IgG in paired sera confirms secondary dengue infection.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.