The viral load test measures the amount of virus particles in a small amount of blood. Doctors call this your viral load (or plasma viral load).

Your result is an indication of how well your body is dealing with HIV:

• If your viral load is high, for example more than 55,000 copies per milliliter (ml) it means there is a lot of virus in your blood and your body isn't fighting the virus well.
• If your viral load is low, there isn't much virus in your body.
• It is best to have a low viral load because it means that your immune system is keeping the virus at bay.
• Even better is to have what doctors call an undetectable level of virus. This means that you have so little virus in your blood that the test can't find the virus even though you're HIV-positive.
• You'll have many viral load tests to track how your body is dealing with HIV. Your doctor will usually do a viral load test at the time you're diagnosed with HIV and then repeat it every few months. You might also have the test when you change your medications or if your condition gets worse.
• Doctors use your viral load results to help them decide when to start drug treatment and when to change your medication.

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment. ©BMJ Publishing Group Limited 2008. All rights reserved.