Assessment of a Real-Time PCR for the Efficacy Monitoring of Antimalarial Treatment

Abstract

The objective of this study was to assess a Real-Time PCR for the efficacy monitoring of antimalarial treatment. The assay compared microscopy with Real-Time PCR for assessing the efficacy of artesunate-mefloquine combination in the treatment of falciparum malaria patients. Thirty six patients with uncomplicated falciparum were selected from fifty patients. Thick peripheral blood smears were taken on day 0, 3, 7, 14 and 28. The ratio of male and female was 4:1. The ratio of Thai and Burmist was 2:7.

The results showed that all thick blood films of 36 patients were positive while the Real-Time PCR showed 33 positive for falciparum (T_m73-74°C) and 3 positive for vivax (T_m76-77°C). The thick blood film of 165 samples from 33 patients was negative. 16.33 % of these samples were positive when testing with Real-Time PCR. The thick blood film sample of 6 patients from 36 patients was negative on day 3, 7, 14 and 28 after treatment while the results of Real-Time PCR were P. falciparum on day 3 and 28 in 3 and 1 patients respectively. The real-time PCR showed positive P.vivax on day 7 in 2 patients.

The results showed that thick blood film had a lower sensitivity than the Real-Time PCR method. However, microscopic detection remains the most reliable standard. In this result we classified every negative thick smear corresponding to a positive Real-Time PCR results as a false negative. Furthermore, the important finding in this study is that 16.67 % of treatment failure were detected by the Real-Time PCR method while, 5.56 % of treatment failure were detected by thick blood film. The Real-Time PCR method is useful for in vivo drug efficacy studies. It is important to detect resistant malaria parasites before they reach high resistance level.