A 28-year-old man presents on the third day of high-grade fever with severe myalgia, retro-orbital pain and a platelet count of 90,000 per microlitre. Dengue is suspected. Which investigation has the highest diagnostic yield at this stage of illness?

• A Dengue IgM capture ELISA
• B Dengue IgG ELISA
• C Haemagglutination inhibition test on paired sera
• D NS1 antigen detection ✓

Explanation

Dengue NS1 antigen is detectable from day 1 to approximately day 7 to 9 of fever, making it the best single test during the first week. IgM capture ELISA becomes positive only around day 5 onwards and peaks in the second week, so it may be falsely reassuring on day 3. IgG rises later still, and paired sera for haemagglutination inhibition require convalescent samples weeks apart, which cannot guide management acutely.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.