HIV viral load
At a Glance
Why Get Tested?
To monitor the status of HIV disease and to guide therapy. Your viral load levels are usually used as an indicator of how well your immune system is dealing with HIV. If you are on anti-HIV treatments, it can be an indictor of how well the treatments are working.
When to Get Tested?
When first diagnosed with HIV, every 4 weeks at the start of therapy, and every 4 months during long-term therapy, or as your doctor recommends
Sample Required?
A blood sample drawn from a vein in your arm
The Test Sample
What is being tested?
This test measures the amount of HIV in your blood. There is still concern that there is a lot of virus in other places in the body, not just the blood - only 2% of HIV is circulating in the blood, the rest is in the lymph system and other body tissue. Early results indicate that changes in viral load in the blood are mirrored in the lymph system, but research is ongoing. "Viral load" means the number of HIV particles or copies of the virus present in the blood.
How is the sample collected for testing?
A blood sample is drawn by needle from a vein in your arm.
The Test
How is it used?
The viral load test provides important information that is used in conjunction with the CD4 cell count:
- to monitor the status of HIV disease,
- to guide recommendations for therapy, and
- to predict the future course of HIV.
Evidence shows that keeping the viral load levels as low as possible for as long as possible decreases the complications of HIV disease and prolongs life.
Public health guidelines state that treatment should be considered for asymptomatic HIV-infected people who have viral loads higher than 100,000 copies per milliliter of blood.
There are several methods for testing viral load; results are not interchangeable so it is important that the same method be used each time.
When is it requested?
A viral load test is ordered when a patient is first diagnosed with HIV. The test result functions as a baseline measurement that shows how actively the virus is reproducing and whether treatment is immediately necessary.
If and when therapy is started, your doctor may request a viral load test and a CD4 count about every four weeks to evaluate whether therapy is being effective. To monitor long-term therapy, your doctor will request viral load tests and CD4 counts about every four months.
What does the test result mean?
Viral load tests are reported as the number of HIV copies in a milliliter of blood. If the viral load measurement is high, it indicates that HIV is reproducing and that the disease will likely progress faster than if the viral load is low. A high viral load can be anywhere from 5,000 to 10,000 copies and can range as high as one million or more.
A low viral load is usually between 200 to 500 copies, depending on the type of test used. This result indicates that HIV is not actively reproducing and that the risk of disease progression is low.
A viral load result that reads 'undetectable' does not mean that you are cured. It may mean that the level of HIV virus in your blood is below the threshold needed for detection by this test. Other tests that are ultra-sensitive and that can measure as few as 20 to 40 copies in a milliliter of blood can be performed to make sure.
Change in viral load is also a very important measurement. A rising count indicates an infection that is getting worse, while a falling count indicates improvement and suppression of the HIV infection.
A non-infected person should have no circulating HIV virus in his or her blood and, therefore, a negative or undetectable viral load.
Is there anything else I should know?
Viral load testing should not be used for diagnosing HIV; the HIV antibody test is still the preferred method of choice for this.
Viral load testing done by the PCR method is incredibly sensitive, which can give rise to false-positive results.
Common Questions
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Article Sources
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