HIV: seroconversion and diagnosis

HIV seroconversion is symptomatic in 60-80% of patients and typically presents as a glandular fever type illness. Increased symptomatic severity is associated with poorer long term prognosis. It typically occurs 3-12 weeks after infection

Features

• sore throat
• lymphadenopathy
• malaise, myalgia, arthralgia
• diarrhoea
• maculopapular rash
• mouth ulcers
• rarely meningoencephalitis

Diagnosis

• HIV antibodies
  • may not be present in early infection, but most people develop antibodies to HIV at 4-6 weeks but 99% do by 3 months
  • usually consists of both a screening ELISA (Enzyme Linked Immuno-Sorbent Assay) test and a confirmatory Western Blot Assay
• p24 antigen
  • a viral core protein that appears early in the blood as the viral RNA levels rise
  • usually positive from about 1 week to 3 - 4 weeks after infection with HIV

<aside> 💡

combination tests (HIV p24 antigen and HIV antibody) are now standard for the diagnosis and screening of HIV

• if the combined test is positive it should be repeated to confirm the diagnosis

• some centres may also test the viral load (HIV RNA levels) if HIV is suspected at the same time </aside>

• testing for HIV in asymptomatic patients should be done at 4 weeks after possible exposure

• after an initial negative result when testing for HIV in an asymptomatic patient, offer a repeat test at 12 weeks