Partial artemisinin resistance, mediated by Plasmodium falciparum K13 (PfK13) mutations, has been confirmed in certain areas of East Africa that are historically associated with high-level ...antimalarial resistance. The Democratic Republic of Congo (DRC) borders these areas in the East. This study aimed to determine the prevalence of resistance markers in six National Malaria Control Program surveillance sites; Boende, Kabondo, Kapolowe, Kimpese, Mikalayi, and Rutshuru.
The single nucleotide polymorphisms (SNPs) in P. falciparum genes PfK13, Pfdhfr, Pfdhps, Pfmdr1, and Pfcrt were assessed using targeted next-generation sequencing of isolates collected at enrollment in therapeutic efficacy studies.
PfK13 SNPs were detected in two samples: in Kabondo (R561H) and in Rutshuru (P441L), both areas near Uganda and Rwanda. The Pfdhps ISGEGA haplotype, associated with reduced sulfadoxine-pyrimethamine chemoprevention efficacy, ranged from 0.8% in Mikalayi (central DRC) to 42.2% in Rutshuru (East DRC).
R561H and P441L observed in eastern DRC are a concern, as they are associated with delayed artemisinin-based combination therapies-clearance and candidate marker of resistance, respectively. This is consistent with previous observations of shared drug resistance profiles in parasites of that region with bordering areas of Rwanda and Uganda. The likely circulation of parasites has important implications for the ongoing surveillance of partial artemisinin-resistant P. falciparum and for future efforts to mitigate its dispersal.
In 2005, the Democratic Republic of the Congo (DRC) switched to artesunate/amodiaquine as the first-line antimalarial in response to increasing sulfadoxine/pyrimethamine resistance and adopted ...intermittent preventive treatment using sulfadoxine/pyrimethamine in pregnancy.
To determine the prevalence of molecular markers of sulfadoxine/pyrimethamine resistance in southwestern DRC 10 years after the new policy was instituted.
From March 2014 to December 2015, blood samples were collected from symptomatic patients presenting to outpatient centres in urban and rural areas. A total of 2030 confirmed Plasmodium falciparum isolates were genotyped at codons associated with sulfadoxine/pyrimethamine resistance.
The prevalence of pfdhfr-N51I, C59R and S108N and pfdhps-A437G mutations was consistently high; the prevalence of the pfdhps-K540E mutation was low but increased since its first report in 2008 in the same region, reaching 17.6% by 2015. The pfdhps-A581G mutation increased from ∼4.5% in 2014 to ∼14.0% in 2015 at urban sites while in rural areas it remained low (∼4.0%). The mutations pfdhfr-I164L and pfdhps-A613S were detected for the first time in DRC. Also, 11 (0.8%) isolates revealed the presence of the newly described pfdhps-I431V mutation. Combining pfdhfr and pfdhps alleles, quintuple and sextuple mutations were observed, with the emergence of septuple (IRNI/IAGEGA)- and octuple (IRNI/VAGKGS)-mutant genotypes.
Intermittent preventive treatment using sulfadoxine/pyrimethamine during pregnancy remains warranted in southwestern DRC. However, the expansion of pfdhps-K540E mutation and emergence of mutants that cause higher levels of sulfadoxine/pyrimethamine resistance is concerning and may present a challenge for future preventive interventions in the country.
Rapid diagnostic tests (RDTs) detecting histidine-rich protein 2 (HRP2) and HRP3 are widely used throughout sub-Saharan Africa (SSA) to diagnose Plasmodium falciparum malaria. However, multiple SSA ...countries have reported pfhrp2 and pfhrp3 (pfhrp2/3) gene deletions. Blood samples (n = 1109) collected from patients with P. falciparum infection from six health facilities throughout the Democratic Republic of the Congo (DRC) from March 2017 to January 2018 were evaluated for pfhrp2/3 deletions. Samples were assayed for HRP2, pan-Plasmodium LDH (pLDH) and aldolase (pAldolase) antigens by bead-based multiplex antigen assay. Samples with low HRP2 concentration compared to pLDH and pAldolase antigens were selected for further pfhrp2/3 genotyping PCRs. The majority of blood samples (93.3%, 1035/1109) had high concentrations of the HRP2 antigen. Single deletions of pfhrp2 were identified in 0.27% (3/1109) of screened samples, with one sample from each of the Kapolowe, Mikalayi, and Rutshuru study sites. A pfhrp3 single deletion (0.09%, 1/1109) was found in the Kapolowe site. Dual pfhrp2 and pfhrp3 deletions were not observed. Due to, the low numbers of pfhrp2 deletions and the sporadic locations of these deletions, the use of HRP2-based RDTs appears to still be appropriate for these locations in DRC.
The spread of drug resistance to antimalarial treatments poses a serious public health risk globally. To combat this risk, molecular surveillance of drug resistance is imperative. We report the ...prevalence of mutations in the Plasmodium falciparum kelch 13 propeller domain associated with partial artemisinin resistance, which we determined by using Sanger sequencing samples from patients enrolled in therapeutic efficacy studies from 9 sub-Saharan countries during 2014–2018. Of the 2,865 samples successfully sequenced before treatment (day of enrollment) and on the day of treatment failure, 29 (1.0%) samples contained 11 unique nonsynonymous mutations and 83 (2.9%) samples contained 27 unique synonymous mutations. Two samples from Kenya contained the S522C mutation, which has been associated with delayed parasite clearance; however, no samples contained validated or candidate artemisinin-resistance mutations.
Routine assessment of the efficacy of artemisinin-based combination therapies (ACTs) is critical for the early detection of antimalarial resistance. We evaluated the efficacy of ACTs recommended for ...treatment of uncomplicated malaria in five sites in Democratic Republic of the Congo (DRC): artemether-lumefantrine (AL), artesunate-amodiaquine (ASAQ), and dihydroartemisinin-piperaquine (DP). Children aged 6-59 months with confirmed Plasmodium falciparum malaria were treated with one of the three ACTs and monitored. The primary endpoints were uncorrected and polymerase chain reaction (PCR)-corrected 28-day (AL and ASAQ) or 42-day (DP) cumulative efficacy. Molecular markers of resistance were investigated. Across the sites, uncorrected efficacy estimates ranged from 63% to 88% for AL, 73% to 100% for ASAQ, and 56% to 91% for DP. PCR-corrected efficacy estimates ranged from 86% to 98% for AL, 91% to 100% for ASAQ, and 84% to 100% for DP. No pfk13 mutations previously found to be associated with ACT resistance were observed. Statistically significant associations were found between certain pfmdr1 and pfcrt genotypes and treatment outcome. There is evidence of efficacy below the 90% cutoff recommended by WHO to consider a change in first-line treatment recommendations of two ACTs in one site not far from a monitoring site in Angola that has shown similar reduced efficacy for AL. Confirmation of these findings in future therapeutic efficacy monitoring in DRC is warranted.
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