Both microscopy and RDT tests can diagnose malaria and are often used together; however they are not identical in their characteristics.
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In ideal conditions a well-trained microscopist with experience in malaria, viewing a well-prepared thick blood film using a good quality microscope may detect with equal or better sensitivity than an RDT test.
In less ideal conditions where equipment, staining quality, or microscopic experience is less good, then RDTs may have equivalent or superior sensitivity to microscopy (including many malarial endemic regions where microscopy may be unavailable or where the sensitivity of microscopy is limited by training, equipment or facilities). RDTs aso provide a more rapid turnaround time allowing emergency use and rapid decision-making.
For species identification thin films are preferred to thick films or RTDS (including mixed infections), as they also allow more accurate identification of sepecies and the % of infected red-cells (for P.falciparum or P.knowlesi).