Babu, a 28-year-old man, presents with a history of exposure three weeks ago, along with cervical lymphadenopathy and hepatosplenomegaly. Which test is used to diagnose HIV in this scenario?

Explanation

In the early stages of HIV infection, particularly within the first few weeks after exposure, the P24 antigen test is used to detect the virus before antibodies are formed. ELISA and Western blot detect antibodies which may not be present yet, and lymph node biopsy is not a diagnostic tool for HIV. Therefore, P24 antigen detection is the appropriate test for early diagnosis.