Sensitivity of malaria diagnosis in blood samples by PCR assay: A comparison with microscopy

This research was undertaken to compare the accuracy of Polymerase Chain Reaction, simple and nested assays, in detecting the DNA of the malaria parasite Plasmodium falciparum, to that of expert microscopy, the most commonly used method. Microscopy must detect the whole parasite, whereas PCR can detect only the presence of the parasite’s DNA, which is useful when the parasite is in the dormant stage. DNA was extracted from whole blood samples (collected on IsoStyxTM) and amplified in a thermocycler. The amplified DNA was separated using 2 % agarose gel electrophoresis. The products were then differentiated by fragment size, depending on the target product. Primers rPLU5, rPLU6, FAL 1, FAL 2, Plasmodium-specific, PL 1473F18, PL 1679R18, and P. falciparum-specific were successful in detecting P. falciparum DNA. Primers UNR, PLF, PLF, FAR, and P. falciparum-specific were also successful, but at lower parasitemia levels. Overall, PCR was found to be as accurate, and, in the case of PLF, far more accurate than microscopy.