HIV testing technologies after two decades of evolution.

Over the past two decades, HIV diagnostics have been essential in detecting and monitoring infection, and continue to play a major role in saving lives throughout the world. As technology evolved, screening, confirmatory, and HIV monitoring assays have been improved and offer better alternatives to address blood screening, surveillance, diagnosis, and patient management. Molecular methods are critical in detecting early infection and for managing patients on anti retroviral therapy whose viral infection may become resistant to therapy. In addition, modifications to conventional methods have introduced new assays, such as sensitive/less sensitive (detuned) assays that can estimate when someone was infected, thereby providing a useful tool for epidemiologic incidence estimates and enrollment into specific intervention programmes for recently infected persons. Many of the newly evolving technologies are essential for use in resource-limited countries because they can address cost issues, limited infrastructure, and a lack of formally trained personnel. Newer rapid HIV kits can be stored in a wide range of temperatures (2-30 degrees C) to address cold-chain issues, can use easily-collected fingerstick blood and oral fluids, and have one-step procedures that are relatively foolproof. Manual CD4 lymphocyte count assays that require only a light microscope and haemacytometer and more simple assays to estimate viral load are appropriate for developing countries where sophisticated instrumentation cannot be supported. Technologic advances with HIV diagnostics continue to address outstanding and new issues associated with diagnosis and the monitoring of infection by providing more simplified, cost-effective, and accurate testing throughout the world.