Clinical Importance
-Viral Load
-Monitoring Treatment
-When To Get Tested

Types of Tests

Getting Tested

Slide Rule

Disease Progression

PCR Tutorial

When to Get Tested Next

The NIH has produced guidelines on testing for viral load and treating HIV infection (8). These recommend:

  • Two measurements of viral load should be made one to two weeks apart to establish baseline viral load. These should be performed about six to nine months after initial infection (if this is known), at the same centre or clinic and at the same time as a CD4 cell count.
  • Viral load should not be measured for one month after acute illness, flu or pneumococcal vaccine as these will increase the amount of circulating virus.
  • If viral load is less than 20,000 - the doctor may recommend starting treatment. According to the guidelines, this decision to initiate treatment is up to the person with HIV and their doctor.
  • If viral load is more than 20,000 - the doctor should start a treatment programme.
  • Viral load should be retested in treated patients four to eight weeks after the start of therapy to assess its effectiveness.
  • Doctors and people with HIV should consider changing therapy if:
    • viral load fails to drop at least five fold
    • viral load does not fall below detectable levels (<500 copies/mL) within four to six months or less than 50 copies within six to eight months
    • viral load rises or drops to undetectable levels and then rises, suggesting resistance to anti-viral therapies
    • CD4 count fails to rise
    • if there is clinical deterioration.
  • Viral load test should be repeated every three to four months in untreated patients.

The aim of treatment is to reduce viral load to undetectable levels (<50 copies/mL) for as long as possible as this is associated with a reduced risk of developing AIDS and a reduced risk of developing resistance to the drugs being taken. For example, a patient with a viral load of 60,000 copies/mL has a high probability (32.6%) of progressing to AIDS within three years whereas one with a viral load of 18,000 copies/mL has a low chance (5.9%) of developing AIDS in the next three years (2).

New diagnostic tests are far more sensitive at detecting HIV and are lowering the level at which viral load can be measured. AMPLICOR HIV-1 MONITOR® Test with UltraSensitive sample preparation method, for example, can detect as little as 50 RNA copies / mL.

More sensitive viral load tests will help to improve our ability to monitor the progress of HIV and the effectiveness of therapy. The NIH guidelines note that reducing viral load below 50 RNA copies / mL "is associated with a more complete and durable viral suppression, compared with reducing HIV RNA to levels between 50-500 copies / mL".

New anti-HIV drugs and potent combination therapies are making it possible to reach such low viral load levels. In recent clinical studies, the SPICE (5) and CHEESE (6) trials, HIV positive individuals were monitored using AMPLICOR HIV-1 MONITOR® Test with UltraSensitive method and were able to achieve viral loads below the level of detection ie. below 50 RNA copies/mL.


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