Dengue NS1 antigen is detectable in serum during the febrile phase (days 1–5). Which statement best describes the kinetics of dengue antibody responses in secondary dengue compared to primary dengue?
- A IgM antibody rises rapidly to high titers on day 2 in secondary dengue
- B In secondary dengue, IgG rises rapidly to high titers on day 2 and may remain detectable for life; IgM may be low or absent ✓
- C NS1 antigen persists longer in secondary dengue than primary
- D Secondary dengue elicits exclusively IgA antibody responses
Correct answer: B. In secondary dengue, IgG rises rapidly to high titers on day 2 and may remain detectable for life; IgM may be low or absent
Explanation
In primary dengue, IgM peaks at day 5–7 and IgG rises slowly 14 days after onset; in secondary dengue (re-infection with a heterologous serotype), memory B cells produce a rapid and high IgG response detectable from day 2 while IgM may be weak or absent — a 'secondary antibody kinetics' pattern. This enhanced heterologous IgG response (antibody-dependent enhancement theory) is implicated in severe dengue (DHF/DSS) pathogenesis. NS1 antigen levels are comparable or even lower in secondary dengue. IgA is not the primary marker used in dengue serology.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.