Prevalence of molecular markers of anti-malarial drug resistance in Plasmodium vivax and Plasmodium falciparum in two districts of Nepal

Abstract

BackgroundSulphadoxine-pyrimethamine (SP) and chloroquine (CQ) have been used in treatment of falciparum and vivax malaria in Nepal. Recently, resistance to both drugs have necessitated a change towards artemisinin combination therapy (ACT) against Plasmodium falciparum in highly endemic areas. However, SP is still used against P. falciparum infections in low endemic areas while CQ is used in suspected cases in areas with lack of diagnostic facilities. This study examines the prevalence of molecular markers of CQ and SP resistance in P. falciparum and Plasmodium vivax to determine if high levels of in vivo resistance are reflected at molecular level as well.MethodsFinger prick blood samples (n = 189) were collected from malaria positive patients from two high endemic districts and analysed for single nucleotide polymorphisms (SNPs) in the resistance related genes of P. falciparum and P. vivax for CQ (Pfcrt, Pfmdr1, Pvmdr1) and SP (Pfdhfr, Pfdhps, Pvdhfr), using various PCR-based methods.Results and discussionPositive P. vivax and P. falciparum infections were identified by PCR in 92 and 41 samples respectively. However, some of these were negative in subsequent PCRs. Based on a few P. falciparum samples, the molecular level of CQ resistance in P. falciparum was high since nearly all parasites had the Pfcrt mutant haplotypes CVIET (55%) or SVMNT (42%), though frequency of the Pfmdr1 wild type haplotype was relatively low (35%). Molecular level of SP resistance in P. falciparum was found to be high. The most prevalent Pfdhfr haplotype was double mutant CNRNI (91%), while frequency of Pfdhps double mutant SGEAA and AGEAA were 38% and 33% respectively. Combined, the frequency of quadruple mutations (CNRNI-SGEAA/AGEAA) was 63%. Based on P. vivax samples, low CQ and SP resistance were most likely due to low prevalence of Pvmdr1 Y976F mutation (5%) and absence of triple/quadruple mutations in Pvdhfr.ConclusionsBased on the limited number of samples, prevalence of CQ and SP resistance at molecular levels in the population in the study area were determined as high in P. falciparum and low in P. vivax. Therefore, CQ could still be used in the treatment of P. vivax infections, but this remains to be tested in vivo while the change to ACT for P. falciparum seems justified.

Distribution of Mutations Associated with Antifolate and Chloroquine Resistance among Imported Plasmodium vivax in the State of Qatar

“…Our observation corroborates the previous reports from Pakistan, Nepal, and Sudan. [39][40][41] However, no triple/quadruple mutations were detected, which is in contrast with previous findings from India 16,36 as India has different degrees of malaria endemicity, and the levels of mutations from the different geographical state is also varied. 42 With regard to the Pvdhps gene, majority of our isolates (77.2%) carried wild type alleles and frequency of single mutant (383G) and double mutant genotypes (383G/553G) was 10.2% and 12.6%, respectively, which have been found to be directly related to sulphadoxine resistance 43 and associated with reduced sensitivity to both sulfa drugs and sulfones.…”

Selective sweep and phylogenetic models for the emergence and spread of pyrimethamine resistance mutations inPlasmodium vivax

“…Pyrimethamine resistance has been investigated in a number of different geographical regions and strong evidence exists that F57L/I (TT A / A T A ), S58R (AG A ), T61M (A T G), S117N/T (A A C/A C C) and I173L/F ( C TT/ T TT) SNPs are responsible for resistance in P. vivax (Hawkins et al, 2007). Subsequent work has consistently shown that F57L/I (TT A / A T A ), S58R (AG A ), S117N/T (A A C/A C C) single mutations and S58R (AG A ) /S117N/T (A A C/A C C) double mutations are widely distributed in different geographical regions of south Asia (Auliff et al, 2006; Brega et al, 2004; de Pecoulas et al, 1998; Hastings et al, 2005; Imwong et al, 2003; Kaur et al, 2006; Kuesap et al, 2011; Lu et al, 2012; Mint Lekweiry et al, 2012; Ranjitkar et al, 2011; Schunk et al, 2006). Previous studies in Pakistan have shown that the S58R (AG A )/S117N (A A C) double mutation and S117N (A A C) single mutation conferring pyrimethamine resistance were present in different cities of the Punjab, Sindh and KPK provinces (Khattak et al, 2013; Zakeri et al, 2011).…”

In vitro chloroquine resistance for Plasmodium vivax isolates from the Western Brazilian Amazon

“…Suwanarusk et al [24] studying the same gene, found that CQ IC50 was significantly higher in P. vivax isolates carrying the Y976F mutation than in isolates with the wild-type allele. Ranjitkar et al [25] found that the low resistance to CQ was due to the low prevalence of mutation Y976F in pvmdr1 (5%). However, most studies did not find any association between mutation in the pvmdr-1 gene and CQ-resistance corroborating these results [16,21,26,27].…”