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Human immunodeficiency virus

Human immunodeficiency virus

Infection: Human immunodeficiency virus (HIV)

Brief description:
  • 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. 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 45 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.