YOU ARE HERE:
Viral load
Viral load is the term used to describe the amount of HIV in your blood. The more HIV in your blood, the faster your CD4 cells are likely to disappear, and the greater your risk of developing symptoms or further illness within the next few years.
What is the viral load test?
Viral load tests estimate the number of HIV particles in the liquid, or plasma part of the blood. They do this by looking for HIV's genes, which are called HIV RNA.
The result of a viral load test is described as the number of copies of HIV RNA per millilitre.
There are several different viral load tests in use at the moment. Each test uses a different technique to measure the number of HIV particles, but all the tests are equally reliable at determining whether your viral load is low, medium or high.
By and large, all the viral load tests are now equally accurate at measuring types of HIV which are common in Africa and Asia. In the past, some tests couldn't always pick up these HIV strains.
However, HIV strains in different parts of the world are always changing and mixing with one another, and there is a risk that the tests will be unable to pick up new strains of HIV. If your viral load result does not seem right (for example, low when your CD4 count is also low), several different viral load tests may be used to get a more accurate picture.
Natural variations
Viral load measurements can rise and fall from one blood sample to the next but this may have no long-term impact on the health of the person being tested.
Researchers have investigated viral load changes in people not on treatment and found that two separate tests on the same sample of blood can give results which differ by as much as three fold. For example, this means that you shouldn't necessarily be worried if your viral load goes up from 5,000 to 15,000 at a time when you are not on treatment.
Similarly, a rise from 50,000 to 100,000 if you aren't on treatment may not be significant, although it may seem like a big increase. Viral load appears to have doubled, but it's within the margins of error for this test.
Your viral load should ideally only be measured when you are well. If you have an infection or have recently had a vaccination, your viral load could temporarily increase.
Significant changes
The time to be concerned is when viral
load results over several months show an upward trend, or when the increase is greater than threefold.
For example, a rise from 5,000 to 25,000 is significant. It represents a fivefold increase in the amount of virus in your blood since your last viral load test.
However, it is still best to confirm this trend on a repeat test.
The effects of vaccinations and infections
If you currently have an infection or have recently received a vaccination, you may have a temporary increase in your viral load. In these cases it is best to avoid having a viral load test for at least one month after a vaccination or illness.