A 22-year-old man presents with fever for 3 days, headache and retro-orbital pain during a dengue outbreak in his town. Platelet count is 1.4 lakh/mm3. Which diagnostic test is MOST appropriate at this point in illness?
- A Dengue IgM capture ELISA
- B NS1 antigen detection by ELISA ✓
- C Dengue IgG ELISA to confirm secondary infection
- D Peripheral blood smear for malaria parasites
Correct answer: B. NS1 antigen detection by ELISA
Explanation
NS1 antigen circulates from day 1 to approximately day 5 of fever, so it is the ideal test in the first five days of febrile illness, exactly matching this patient on day 3. IgM antibodies usually become detectable only from around day 5 onward, so IgM ELISA would frequently be falsely negative this early. The platelet count here is normal and does not change the diagnostic choice, and a malaria smear answers a different differential rather than confirming dengue.
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.