Most physicians and scientists recommend that everyone who is HIV positive should have a viral load test as part of their initial evaluation soon after HIV positive status is diagnosed. This will help doctors determine the stage of disease and provide information helpful in deciding whether treatment should be started. As viral load generally rises just after infection with HIV, people are advised to wait about six to nine months before taking a viral load test by which time the levels of virus in the blood will be stable (baseline viral load).
For many people the exact date of infection can be unknown. Their doctors will probably advise having a viral load test as part of the initial evaluation as soon as HIV positive status is diagnosed.
After baseline viral load has been determined, it is advisable for HIV positive people to be tested every four months while they are not receiving any treatment. Once treatment is started, viral load may be tested more frequently to make sure the drugs are working effectively.
For the most accurate results patients should make sure they are tested for viral load at the same clinic, using the same testing method. They should notify their doctor if they have been sick or had a vaccination recently, as this can increase viral load abnormally, leading to incorrect results.
To obtain a measure of baseline viral load, two tests should be performed one to two weeks apart. Viral load should not be measured for one month after sickness or vaccinations as these may increase the amount of circulating HIV virus.
Viral load is an indicator of disease progression in infants as well as adults (1) and assessing blood samples is also important in this group of HIV positive individuals. Research shows that viral load in babies rises sharply in the first few months of life before falling and that a higher peak viral load in early life is associated with rapid disease progression.
Measuring viral load is advisable for pregnant women as it provides an indication of risk of HIV transmission to the baby. Studies have suggested that the transmission to the foetus is related to viral load; the lower the amount of virus in the mothers blood the less likely the foetus will become infected (2). As Caesarean section protects against mother-to-infant transmission, a measure of viral load before delivery may help women decide on the method of birth.
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