viral load

Viral load is a measure of the amount of viral particles of RNA in the blood, and is reported as “copies per millilitre”. With early infection this number is often as high as one million. High set points, e.g. over 100,000 copies/ml, are associated with a higher risk of disease progression, i.e. developing AIDS and death. Antiretroviral therapy (ART) can lower the viral load in the blood to a level lower than our ability to measure it – this is then called an ‘undetectable’ viral load. A person on ART who achieves this level is still HIV+ and still able to spread the virus. Determination of viral load is part of the therapy monitoring during chronic viral infections and in immunocompromised patients. Viral load can be measured using either probes (bDNA) or polymerase chain reaction (PCR).

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International Union of Immunological SocietiesUniversity of South AfricaInstitute of Infectious Disease and Molecular MedicineElizabeth Glazer Pediatric Aids FoundationStellenbosch University