Viral load

A viral load [1]A measurement of the quantity of HIV RNA in the blood. Viral load blood test results are expressed as the number of copies (of HIV) per milliliter of blood plasma. test measures the concentration of free virus in the blood. ‘Free’ means the HIV that is not inside cells. The higher the viral load, the more active HIV is considered to be.

A viral load test, together with a T-cell count, is used to help make treatment decisions. An undetectable or low viral load normally means that your immune system together with your HIV treatments, if you are on them, are successfully containing HIV from replicating in your body. Results of the viral load test are usually given as the number of viral copies per ml. of blood.

• More than 30,000 is considered high
• 10,000 – 30,000 is considered moderate
• Less than 10,000 is considered low

It is important to remember that undetectable viral load does not equal zero viral load, but rather means that the amount of virus is below the level that can currently be measured by available tests.

The risk of HIV transmission during unsafe sex may be related to the viral load of the positive person. Generally, it is thought to be that the risk of transmission is lower if viral load is lower, and that the risk is higher when viral load is higher. However, even though this general relationship is true, there are a number of reasons why viral load is not a good way to measure HIV transmission risks during sex. They are:

1. Viral load is a measure taken from the blood. Other body fluids such as semen are usually involved in the sexual transmission of HIV. Although they are generally correlated, the viral load levels in semen and blood can be quite different. In particular, some infections, for example sexually transmitted infections, can cause viral load in semen to fluctuate rapidly.
2. There is evidence that if the viral load in your body falls or rises, there will be some delay before the viral load in your semen changes. So, if your blood’s viral load drops to undetectable, you can’t be certain when the viral load in your semen will drop.
3. Viral load can vary quite quickly from day to day – for example if you have other infections. It can take weeks to get the results of a viral load test. Even if your viral load was low when your blood was taken, it doesn’t mean it is still low. Treatment breaks can alter your viral load.
4. The viral load test is a measure of ‘free’ virus. HIV also lives inside the cells of your body. Once HIV gets into your cell’s genetic material, it stays there until the cell dies. Treatments prevent new cells becoming infected and can also prevent the production of viruses [2]A small infective organism which is incapable of reproducing outside a host cell. from infected cells, but they do not remove HIV from the cell’s genetic material. HIV infected cells can survive for long periods. These cells can exist in both blood and semen and can be transmitted during unsafe sex.