Antimalarial drug resistance in the Central and Adamawa regions of Cameroon: Prevalence of mutations in P. falciparum crt, Pfmdr1, Pfdhfr and Pfdhps genes

Abstract

The spread of Plasmodium falciparum resistant parasites remains one of the major challenges for malaria control and elimination in Sub Saharan Africa. Monitoring of molecular markers conferring resistance to different antimalarials is important to track the spread of resistant parasites and to optimize the therapeutic lifespan of current drugs. This study aimed to evaluate the prevalence of known mutations in the drug resistance genes Pfcrt, Pfmdr1, Pfdhfr and Pfdhps in two different epidemiological settings in Cameroon. Dried blood spots collected in 2018 and 2019 from asymptomatic individuals were used for DNA extraction and then the Plasmodium infection status was determined byPCR. Detection of SNPs was performed by nested PCR followed by allele-specific restriction analysis (ASRA). The prevalence of each genotype was compared between sites using the Chi square and Fisher’s exact tests. A high prevalence of the Pfcrt K76 wild type allele was found in both sites (88.5 and 62.29% respectively; P< 0,0001). The prevalence of Pfmdr1 mutations 86Y and 1246Y was respectively 55.83 and 1.45% in Mfou and 45.87 and 5.97% in Tibati, with significant difference between the studied areas (P<0.0001). Overall, the Pfdhfr triple-mutant genotype (51I/59R/108N) was highly prevalent (> 96%), however no SNP was detected at codon 164. In Pfdhps, the prevalence of the 437G mutation reached (90%) and was at higher frequency in Mfou (P< 0.0001). Overall, the Pfdhps mutations 540E and 581G were less common (0.33 and 3.26%, respectively). The quadruple resistant genotype (Pfdhfr 51I/59R/108N+Pfdhp437G) was found almost 90% of the samples. The wild-type genotype (Pfdhfr N51/C59/S108/164I+Pfdhps A437/K540/A581) was never identified and the sextuple mutant (Pfdhfr 51I/59R/108N+Pfdhp437G/540E/581G), kwon as super resistant appeared in two samples from Tibati. These findings demonstrate declining trends in the prevalence of mutations conferring resistance to 4-aminoquinolines, especially to chloroquine. However, a high level of mutations in P. falciparum genes related to SP resistance was detected and this raises concerns about the future efficacy of IPTp-SP and SMC in Cameroon.

Assessment of genetic polymorphisms associated with malaria antifolate resistance among the population of Libreville, Gabon

“…On comparing with the high multiple mutations sets documented in Nigeria [ 51 ] and Kenya [ 52 ], where various SNPs increased the double, triple, and quadruple mutation sets in Pfdhfr , likewise NRNL, IRSI, ICNI, and ICNL multiple mutation sets were expressed among the current studied population. In addition, contrary to the I 164 U finding in individuals with malaria infection living with human immunodeficiency virus, I 164 L mutation, which is rarely reported in Central Africa [ 34 , 49 , 53 ] and somewhat reported in East and South Africa and Asia [ 54 – 56 ], was detected in two isolates of the Gabon population of the current study. Thus, these findings indicate the importance of regularly checking the status of the polymorphisms that induce drug resistance.…”

Influence of the sickle cell trait on Plasmodium falciparum infectivity from naturally infected gametocyte carriers

“…In our studied area, about two third of the children (65.5%) presented Plasmodium infection and 95% of the infections harboured P. falciparum, in line with our previous works in the same locality of Mfou [ 31 – 33 ]. P. falciparum prevalence has even increased over the past 15 years, from 51% in 2005–2006, 55% in 2013–2014 to 66% in 2017 and 2018, despite continued control interventions.…”

Geographical emergence of sulfadoxine-pyrimethamine drug resistance-associated P. falciparum and P. malariae alleles in co-existing Anopheles mosquito and asymptomatic human populations across Cameroon

“…This is of major concern since the Pfdhps 437 G marker is associated with partial parasite resistance to sulfa drugs. The Pfdhps K540E mutation linked with full resistance was identified only in a single isolate, confirming the low prevalence of this allele in Cameroon similar to previous studies ( 23 , 24 ).…”

“…While the current SP formulation combines a partner drug, the persistent drug pressure still selects for drug resistance phenotypes that may culminate in the loss of drug efficacy for malaria control. This is supported by the saturation of the Pfdhfr IRN triple-mutant alleles in synergy with a high frequency of the Pfdhps A437 G mutation in both host systems suggesting that resistance alleles to pyrimethamine and sulfadoxine are increasingly selected in the field ( 23 , 24 ). This is of major concern since the Pfdhps 437 G marker is associated with partial parasite resistance to sulfa drugs.…”