HIV testing, PrEP, and PEP — KFP-style written assessment

KFP 1 (10 marks)

A 29-year-old man presents with five days of fever, sore throat, macular rash and cervical lymphadenopathy. He had receptive anal intercourse without condoms 12 days ago with a new partner. A fourth-generation HIV antigen/antibody test is negative. Monospot is negative. ^{[9] [8]}

1. What is the leading diagnosis and why does the negative test not exclude it? (4) ^[9]
2. Which test should you send now and what result pattern would confirm the diagnosis? (4) ^[9]
3. Outline his immediate management once confirmed. (2) ^[6]

Model answers

1. Acute retroviral syndrome (primary HIV infection): fever, pharyngitis, macular rash and lymphadenopathy 2-6 weeks after a high-risk exposure; symptoms are nonspecific and misdiagnosis as glandular fever is common. The fourth-generation assay is negative because antibody has not yet seroconverted — he is inside the window period. ^{[9] [8]}
2. Send HIV RNA (viral load) now — it is the most useful test in this phase because antibody is negative or indeterminate. A high RNA with a negative antigen/antibody confirms acute infection (after repeating to exclude lab error). ^[9]
3. Link urgently to specialist care for early antiretroviral therapy — individual benefit plus immediate transmission control during the high-viral-load phase; notify and test partners; screen for other STIs. ^[6]