Prevalence of <em>Plasmodium falciparum</em> antimalarial drug resistance genes in Southeastern Gabon from 2011 to 2014

Abstract

PurposeThe introduction of artemisinin-based combination therapies (ACTs) in treating uncomplicated malaria and sulfadoxine–pyrimethamine (SP) as intermittent preventive treatment during pregnancy drastically decreased the burden of malarial disease around the world. However, ACTs are known to select for drug resistance markers. In Gabon, artemether–lumefantrine induced an increase in the prevalence of N86-Pfmdr1, which is associated with treatment failure. However, little data are available regarding resistance markers in Southeastern Gabon. This study aimed to evaluate the evolution of resistance haplotypes in the Pfcrt, Pfdhps, Pfdhfr, and PfK13 genes from 2011 to 2014 in Southeastern Gabon.MethodsA total of 233 Plasmodium falciparum DNA samples were collected from febrile pediatric patients in South Gabon: Franceville, an urban area; Koulamoutou, a semi-urban area; and Lastourville, a rural area. Pfcrt, Pfdhps, Pfdhfr, and the propeller domain of PfK13 were sequenced for all isolates.ResultsThe overall prevalence (3.7%–11.5%) of the wild-type haplotype Pfcrt 72-76 CVMNK was not significantly different between 2011 and 2014 in Southeast Gabon. For Pfdhfr (codons 51, 59, 108, 164), the IRNI triple-mutant haplotype was the most prevalent (>89.0%). The ICNI and NCNI mutant haplotypes and the NCSI wild-type haplotype showed a minor prevalence. There were no differences in the distributions of these haplotypes across the 4 years and the three study sites. For Pfdhps, the AAKAA and SGKAA mutant haplotypes and the SAKAA wild-type haplotype were similarly present in the three areas during the study period. The AGKAA double mutant was first observed in 2013 in Franceville and in 2014 in Koulamoutou and Lastourville. Interestingly, only the A578S mutation (0.4%) and two new A494V (0.4%) and V504A (0.9%) mutations were found in PfK13.ConclusionDespite the withdrawal of chloroquine, the frequency of the resistant allele 76T remained high in the south of Gabon. Moreover, a high level of resistant haplotypes against IPTp-SP was found.

Molecular surveillance of Pfcrt and k13 propeller polymorphisms of imported Plasmodium falciparum cases to Zhejiang Province, China between 2016 and 2018

“…In this study, 19 alleles were identified, and eight (P441S, D464E, K503E, R561H, A578S, R622I, V650F, and N694K) were nonsynonymous. Similarly with previous literatures, the propeller domain of the k13 gene showed a limited diversity of alleles in Africa [18,35,36]. Of note is that one of the validated k13 resistance mutations-R561H-was detected in two patients, one each from Rwanda and Myanmar.…”

“…However, R561H might be the first time found from Rwanda [36,37,39]. In addition, mutation A578S identified in one isolate from Cameroon, was also found in other African countries, including Gabon, Uganda, Mali, Kenya and DR Congo [18,[39][40][41], but it was not associated with clinical or in vitro resistance to artemisinin according to previous studies [37,42]. The study also found the uncommon k13 mutation R622I in two cases, one in Mozambique and one in Somalia, and this mutation was initially reported in northwest Ethiopia at the border with Sudan [43].…”

“…The k13 and Pfcrt genes were amplified by nested PCR, as previously described [17,18]. The primers for PCR were described in previous study and they are listed in Additional file 1: Table S1 [17,18]. Proof-reading polymerase was used in each reaction to prevent amplification errors.…”

Amplicon deep sequencing of kelch13 in Plasmodium falciparum isolates from Senegal

“…A578S, found in one sample from the region of Matam with an allele frequency of 2%, has not previously been reported in Senegal, although a different nonsynonymous mutation at the same position (A578D) was reported in Thiès [7]. A578S is the most widespread Pfk13 SNP observed in Africa, having been reported in Mali, Angola, Democratic Republic of the Congo, Uganda, Gabon, Ghana, Congo-Kinshasa, Republic of Congo and Kenya [23][24][25][26][27]. However, it is consistently detected at low frequencies ( Table 1).…”

“…In total, 81 patient samples from three regions of Senegal were selected: Dakar (48), Kédougou (27) and Matam (6), which present different levels of malaria prevalence. In Dakar malaria transmission is low and parasite prevalence is estimated at 1.3% [13].…”