Impact of treatment and re-treatment with artemether-lumefantrine and artesunate-amodiaquine on selection of Plasmodium falciparum multidrug resistance gene-1 polymorphisms in the Democratic Republic of Congo and Uganda

Abstract

BackgroundThe emergence of resistance against artemisinin combination treatment is a major concern for malaria control. ACTs are recommended as the rescue treatment, however, there is limited evidence as to whether treatment and re-treatment with ACTs select for drug-resistant P. falciparum parasites. Thus, the purpose of the present study is to investigate the impact of (re-)treatment using artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL) on the selection of P. falciparum multidrug resistance-1 (Pfmdr1) alleles in clinical settings.MethodsP. falciparum positive samples were collected from children aged 12–59 months in a clinical trial in DR Congo and Uganda. Pfmdr1 single nucleotide polymorphisms (SNPs) analysis at codons N86Y, Y184F, and D1246Y were performed at baseline and post-treatment with either AL or ASAQ as a rescue treatment using nested PCR followed by restriction fragment length polymorphism (RFLP) assays.ResultsThe pre-treatment prevalence of Pfmdr1 N86 and D1246Y varied significantly between the sites, (p>0.001) and (p = 0.013), respectively. There was borderline significant directional selection for Pfmdr1 184F in recurrent malaria infections after treatment with AL in Uganda site (p = 0.05). Pfmdr1 NFD haplotype did not significantly change in post-treatment infections after re-treatment with either AL or ASAQ. Comparison between pre-treatment and post-treatment recurrences did not indicate directional selection of Pfmdr1 N86, D1246 alleles in the pre-RCT, RCT and post-RCT phases in both AL and ASAQ treatment arms. Pfmdr1 86Y was significantly associated with reduced risk of AL treatment failure (RR = 0.34, 95% CI:0.11–1.05, p = 0.04) while no evidence for D1246 allele (RR = 1.02; 95% CI: 0.42–2.47, p = 1.0). Survival estimates showed that the Pfmdr1 alleles had comparable mean-time to PCR-corrected recrudescence and new infections in both AL and ASAQ treatment arms.ConclusionWe found limited impact of (re-)treatment with AL or ASAQ on selection for Pfmdr1 variants and haplotypes associated with resistance to partner drugs. These findings further supplement the evidence use of same or alternative ACTs as a rescue therapy for recurrent P.falciparum infections. Continued monitoring of genetic signatures of resistance is warranted to timely inform malaria (re-)treatment policies and guidelines.

Emerging implications of policies on malaria treatment: genetic changes in thePfmdr-1gene affecting susceptibility to artemether–lumefantrine and artesunate–amodiaquine in Africa

“…For instance, these two drugs could be cycled in national treatment policies, 29 deployed simultaneously in populations 30 or used sequentially in individual patients when the initial treatment fails. 31 Planning for these strategies will benefit from understanding and quantifying the current direction and rates of change in these SNPs in populations in relation to ACT policies and consumption. Here, we collate and map all published Pfmdr1 SNP data at positions 86, 184 and 1246 and analyse the effect of implementation of AS-AQ and AL on the temporal trends in the population prevalence of these SNPs across Africa.…”

Drug sensitivity of Plasmodium falciparum field isolates to selected antimalarial drugs in Ghana using the in-vitro DAPI assay

“…Although data from this study seems to suggest an increased tolerance to most of the drugs tested, it does not suggest high treatment failures to the antimalarials currently in use in Ghana despite the fact that we do not have concrete data to support what has been found elsewhere [20]. Again, in vitro studies alone cannot be used to explain treatment failures as it is very complex and involves other several factors including host genetic factors, poor adherence and exposure to subtherapeutic doses as well as management and administrative issues [44][45] In conclusion, we have used the in vitro DAPI assay to assess the sensitivities of over 200 parasites isolates collected over 3 consecutive years from 2 sites of different transmission intensities in Ghana to five drugs (single individual drugs). Although we did see higher resistance levels to all the drugs used over the period (based on the cutoff poits from literature), this does not mean high drug treatment failures because these were tested for individual drugs most of which are used in combinations in Ghana except Chloroquine that is currently not in use in Ghana.…”

Pharmacovigilance of suspected or confirmed therapeutic ineffectiveness of artemisinin-based combination therapies: extent, associated factors, challenges and solutions to reporting

“…Most ACT-failures are reported to supervisors and four in ve reports are entirely verbal, which undermines the availability of analyzable PV data for both current and future use in evaluations of the real-world effectiveness of ACTs in our setting. The availability of high-quality PV data at NPC could permit robust signal detection analyses of ACT-failure and its likely causes, namely; inappropriate treatment, substandard and falsi ed ACTs, misdiagnosis, underestimation of disease severity, nonadherence to treatment, drug resistance, drug interactions or any combination of them [8,9].…”

“…Treatment failure with or therapeutic ineffectiveness of ACTs is a complex outcome with several causes which could include; inappropriate treatment e.g. non-adherence to treatment (wrong dose, wrong duration, wrong indication), substandard and falsi ed medicines, underestimation of disease severity at the time of prescribing, drug resistance, drug interactions and misdiagnosis [8,9]. Some scholars discourage the reporting of drug therapeutic ineffectiveness alongside existing ADR surveillance systems due to the potential for misuse e.g.…”