| Popis: |
Plasmodium falciparum histidine-rich protein 2 (PfHRP2) forms the basis of many current malaria rapid diagnostic tests (RDTs). However, parasites lacking the pfhrp2 gene do not express the PfHRP2 protein and are, therefore, not identifiable by PfHRP2-detecting RDTs. In this study, the performance of the SD Bioline Malaria Ag P.f/Pan RDT together with pfhrp2 variation in Madagascar was evaluated. The study also evaluated pfhrp2 gene variation in PNG. Genomic DNA isolated from patient blood samples from Madagascar (n = 260) and PNG (n = 169) were subjected to molecular detection (18S rRNA PCR, followed by post-PCR LDR-FMA) for the identification of Plasmodium spp. infections. PCR amplification of the pfhrp2 gene, sequencing and gene analysis enabled studying of gene variation. PCR diagnosis showed that 28.8% (75/260) in Madagascar and 81.1% (137/169) in PNG had Plasmodium infections. 94.6% (71/75) and 91.2% (125/137), of the infections were P. falciparum in Madagascar and PNG, respectively. Compared to molecular detection, the sensitivity and specificity of the RDT (in Madagascar) for P. falciparum detection were 87% and 89%, respectively. From randomly selected pfhrp2 gene-positive samples, 16 pfhrp2 gene sequences from Madagascar and 18 pfhrp2 gene sequences from PNG were generated. Although extensive variations of the pfhrp2 gene were observed in both countries, this study showed that there was no indication of pfhrp2 deletion. The study also did not observe a clear correlation between pfhrp2 sequence structure and RDT detection rates. Although the absence of pfhrp2 deletion from the samples screened here is encouraging, continued monitoring of the efficacy of RDTs currently used in Madagascar and PNG is warranted. |
