A Cross-Sectional Survey of Plasmodium falciparum pfcrt Mutant Haplotypes in the Democratic Republic of Congo

Abstract

Abstract. In the Democratic Republic of the Congo (DRC), artesunate-amodiaquine is first-line therapy for falciparum malaria; little is known about the prevalence of molecular markers of parasite drug resistance. Across the DRC, we genotyped 166 parasites in Plasmodium falciparum chloroquine resistance transporter ( pfcrt) using polymerase chain reaction (PCR) and sequencing. Of these parasites, 73 (44%) parasites were pure wild-type CVMNK, 55 (31%) parasites were chloroquine-resistant CVIET, 35 (21.1%) parasites were mixed CVMNK and CVIET, and 3 parasites were other genotypes. Ninety-two infections (55.4%) harbored the pfcrt K76T substitution that is highly correlated with chloroquine failure. The amodiaquine-resistant SVMNT haplotype was absent. Geographically, pfcrt haplotypes were not clearly clustered. Chloroquine accounted for 19.4% of antimalarial use, and amodiaquine accounted for 15.3% of antimalarial use; there were no associations between drug use and mutant haplotype prevalence. In the DRC, our molecular survey indicates that resistance to chloroquine is substantial but that resistance to amodiaquine is absent. These contrasting findings highlight the need for molecular surveillance of drug resistance to inform malaria control policies.Chloroquine (CQ)-resistant Plasmodium falciparum parasites are widespread and undermined prior efforts to control falciparum malaria. Resistance is conferred by polymorphisms in the P. falciparum CQ resistance transporter (PfCRT) 1 encoded by the pfcrt gene. Clinically, the K76T substitution elevates the risk of treatment failure sevenfold.

Falciparum malaria molecular drug resistance in the Democratic Republic of Congo: a systematic review

“…These studies were of samples from 3 to 458 individuals (mean = 142) and that usually were focalized to one or two geographical sites. However, three studies [ 18 , 19 , 21 ] were based on samples collected in the whole country as part of the Demographic and Health Survey (DHS), funded mostly by the international community [ 33 ]. Considering the size of the DRC (second largest African country with 2,345,000 km 2 ) and the different patterns of malaria from one corner to another, results of most of these studies are not generalizable to the nationwide, but must be considered in their local context.…”

Spatial and epidemiological drivers of P. falciparum malaria among adults in the Democratic Republic of the Congo

“…MIPs are a technology for obtaining highly multiplexed deep sequencing data that have recently been applied to Plasmodia species 14 . Using previously generated sequencing data from 1,065 children enrolled in the 2013-14 DRC DHS 14,15 , we assessed single nucleotide polymorphisms (SNPs) of the pfdhps (A437G, K540E, and A581G) and pfcrt (K76T) genes known to be associated with sulfadoxinepyramethamine (SP) and chloroquine resistance, respectively 14,[36][37][38] . We used these individuallevel data to estimate cluster-level prevalence for each SNP using the PrevMap package in R, which fits a spatial model using a Gaussian Process 39 .…”

The Impact of Antimalarial Resistance on the Genetic Structure ofPlasmodium falciparumin the DRC

“…Based on previous findings of an east-west divide in molecular markers of antimalarial resistance in the DRC 8,9 , all samples in the DRC were divided by geographically-weighted K-means clustering into two populations ( Supplemental Figure 7 ). The prevalence of every mutation identified by the drug resistance MIP panel was calculated in eastern and western DRC, as well as at the country level.…”

“…The DRC harbors a large, understudied parasite population that likely serves as a bridge between African parasite populations. Limited previous work has shown that the DRC represents a watershed between East and West African drug resistant parasite populations for sulfadoxine-pyrimethamine and chloroquine resistance 7–9 . More recently, parasite population structuring due to mutations at these and other loci associated with antimalarial resistance has been confirmed within the DRC 10 .…”