Infection: Human immunodeficiency virus (HIV)
- Virus that causes acquired immune deficiency syndrome (AIDS) if untreated.
- The main risk group in NZ are men who have sex with men (MSM), but is seen in others also.
Did you know?
Modern tests are very accurate. Consent to test is a standard requirement (for any test), but complicated pre-test counselling or consent procedures are not required, and should not be a barrier to testing.
Because HIV is now easily treatable, it is generally only a danger to health if undiagnosed. Effective treatment renders people non-infectious to others, thus limiting the spread of HIV.
- This is why there should be a low threshold for testing.
Who should I test?
Testing should be performed in those seeking STI testing, particularly in MSM.
- Periodic testing (at least annually) is recommended in those with risk factors e.g. MSM.
HIV can present in many different ways.
- Test people with unusual presentations, unusual infections, general unexplained decline in health. Testing is simple and straightforward.
Test of choice:
Request HIV serology
Modern tests (called ‘4th generation tests’) detect a combination of antigen (bits of the virus) and antibody (body’s response to the virus).
- These tests become positive much sooner after infection than older tests, where the ‘window period’ could be prolonged because they only detected antibody.
- Excellent sensitivity – a negative test excludes the diagnosis (unless exposure within last 21 days)
- Excellent specificity – a positive test confirms the diagnosis.
Tests to avoid/specialist tests:
HIV viral load (HIV RNA):
- Not recommended as initial diagnostic test for HIV.
- This is generally only used by specialists, and is for monitoring treatment and confirming infection in newly diagnosed patients.