Viral load is a measurement of how much
HIV is present in your blood. A sample of blood is
drawn and sent to a lab for testing. Results are expressed as the number of
copies of the virus per milliliter of blood. Each virus is called a "copy"
because HIV reproduces by making copies of itself (replicating).
The viral load test gives a more accurate picture than a CD4+ cell count of what the virus
is doing in your body at the moment. (The CD4+ test
measures the effect HIV is having on your immune system.) The viral load test
is used to help decide when to change antiretroviral medicines.