A 24-year-old man presents with acute high-grade fever for 3 days, retro-orbital pain and myalgia. Examination shows a platelet count of 1.4 lakh/cumm and no plasma leakage. Which single test will most likely confirm dengue infection at this stage of illness?
- A Dengue IgM ELISA
- B Dengue IgG ELISA
- C NS1 antigen detection ✓
- D Peripheral smear for atypical lymphocytes
Correct answer: C. NS1 antigen detection
Explanation
NS1 antigen is secreted during the acute febrile phase and is detectable from day 1 up to about day 5 of illness, making it the confirmatory test in this patient. IgM ELISA becomes positive only around the fifth day of fever and peaks later, so it would be falsely reassuring on day 3. IgG rises even later and cannot distinguish current from past infection in endemic settings.
Reference: Park's Textbook of Preventive and Social Medicine, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.