A 28-year-old male presenting with fever, lymphadenopathy, pharyngitis, and a transient maculopapular rash tests HIV-1/2 antibody negative but HIV-1 p24 antigen positive by 4th generation combination assay. The most appropriate next step is:
- A Repeat the 4th generation test after 6 weeks
- B Western blot for HIV-1 antibody confirmation
- C Perform HIV-1 RNA viral load (NAAT) for confirmation and baseline viral load ✓
- D Report as HIV-negative as antibody component is negative
Correct answer: C. Perform HIV-1 RNA viral load (NAAT) for confirmation and baseline viral load
Explanation
A 4th generation combination assay detecting p24 antigen before seroconversion (antibody-negative) indicates acute HIV infection in the 'window period'. This requires confirmation by HIV-1 RNA NAAT (viral load), which is highly positive during acute HIV with very high viraemia. Early diagnosis allows prompt ART initiation, which reduces the viral reservoir and prevents transmission. Western blot may be indeterminate during acute infection. Repeating after 6 weeks is the old approach and delays diagnosis.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
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Written and medically reviewed by the StethoPrep medical team.