The detection of Plasmodium falciparum and P-vivax in DNA-extracted blood samples using polymerase chain reaction

Seventeen pairs of published primer sets were compared for their relative sensitivity to detect malaria DNA extracted from blood samples, which were obtained from Pakistani patients suffering from malaria. The primer sets investigated consisted of. (i) 9 pairs of direct primers and 3 sets of nested primers for detecting Plasmodium falciparum, (ii) 2 pairs of direct primers and 2 sets of nested primers for detecting P. vivax, and (iii) 1 set of multiplex primers for detecting both P. falciparum and P. vivax, simultaneously. After a miniscreen of 9 DNA-extracted blood samples using the 17 primer sets stated above, 5 primer sets were short-listed (based on their superior sensitivity) and used for a maxi-screen of DNA extracted from 126 microscopy-positive blood samples from Pakistan, with the following results. (i) For the detection of P. falciparum, the direct primer pair 'PF1+PF2' gave a sensitivity of 95% and the nested primer set 'RIT405+RIT406/RIT371+RIT372' gave a sensitivity of 97%. (ii) For the detection of P. vivax, the direct primer pair 'Forward+Reverse' and the nested primer set 'PLF+UNR/PLF+VIR' both gave a sensitivity of 94%. (iii) The nested multiplex primer set 'rPLU5+rPLU6/rFAL1+rFAL2+rVIV1+rVIV2' gave a sensitivity of 97% and 96% for P. falciparum and P. vivax, respectively. It was concluded that the nested multiplex primer set was the most optimal primer set to use for the detection of malaria DNA extracted from blood samples. Furthermore, the nested multiplex primer set has the advantage of simultaneously detecting and differentiating between P. vivax and P. falciparum.