Prevalence of Plasmodium falciparum Molecular Markers of Antimalarial Drug Resistance in a Residual Malaria Focus Area in Sabah, Malaysia

Abstract

Chloroquine (CQ) and fansidar (sulphadoxine-pyrimethamine, SP) were widely used for treatment of Plasmodium falciparum for several decades in Malaysia prior to the introduction of Artemisinin-based Combination Therapy (ACT) in 2008. Our previous study in Kalabakan, located in south-east coast of Sabah showed a high prevalence of resistance to CQ and SP, suggesting the use of the treatment may no longer be effective in the area. This study aimed to provide a baseline data of antimalarial drug resistant markers on P. falciparum isolates in Kota Marudu located in the north-east coast of Sabah. Mutations on genes associated with CQ (pfcrt and pfmdr1) and SP (pfdhps and pfdhfr) were assessed by PCR amplification and restriction fragment length polymorphism. Mutations on the kelch13 marker (K13) associated with artemisinin resistance were determined by DNA sequencing technique. The assessment of pfmdr1 copy number variation associated with mefloquine resistant was done by real-time PCR technique. A low prevalence (6.9%) was indicated for both pfcrt K76T and pfmdr1 N86Y mutations. All P. falciparum isolates harboured the pfdhps A437G mutation. Prevalence of pfdhfr gene mutations, S108N and I164L, were 100% and 10.3%, respectively. Combining the different resistant markers, only two isolates were conferred to have CQ and SP treatment failure markers as they contained mutant alleles of pfcrt and pfmdr1 together with quintuple pfdhps/pfdhfr mutation (combination of pfdhps A437G+A581G and pfdhfr C59R+S108N+I164L). All P. falciparum isolates carried single copy number of pfmdr1 and wild type K13 marker. This study has demonstrated a low prevalence of CQ and SP resistance alleles in the study area. Continuous monitoring of antimalarial drug efficacy is warranted and the findings provide information for policy makers in ensuring a proper malaria control.

Plasmodium falciparum artemisinin resistance monitoring in Sabah, Malaysia: in vivo therapeutic efficacy and kelch13 molecular marker surveillance

“…Results from this study are consistent with another study from Sabah, which reported only wild-type kelch13 molecular markers using 17 SNPs from 50 P. falciparum isolates collected from 2008 to 2014 [ 30 ]. The absence of P. falciparum artemisinin drug resistance in Malaysia, either spread from imported cases from neighbouring countries harbouring resistant P. falciparum parasites, or de novo resistance arising independently, is likely due in large part to the effective Malaysian malaria public health programme [ 25 ].…”

Population Genetics and Molecular Epidemiology of Eukaryotes

“…The existence and importance of this reservoir could only be uncovered by a molecular method. Molecular surveillance of specific polymorphisms was also used to demonstrate high degrees of susceptibility (61, 70, 73, 87), sustained resistance (60) or high risk for resistance (89) in specific countries. In each case, ongoing molecular surveillance is suggested as an early warning mechanism for the arrival or development of resistance.…”

Molecular Surveillance of Pfkelch13 and Pfmdr1 Mutations in Plasmodium falciparum Isolates from Southern Thailand

“…It is in borders with Malaysia to the south and Myanmar to its upper west. In Malaysia, the incidence of malaria is estimated to be 13 cases per 100,000 populations [26] and the prevalence of antimalarial drug resistance was relatively low [27]. The molecular analysis showed a single copy of Pfmdr1 and wild-type PfKelch13 genes indicating that Malaysia has limited case of artemisinin resistance.…”