Molecular correlates of high-level antifolate resistance in Rwandan children with Plasmodium falciparum malaria.
Antifolate drugs have an important role in the treatment of malaria. Polymorphisms in the genes encoding the dihydrofolate reductase and dihydropteroate synthetase enzymes cause resistance to the antifol and sulfa drugs, respectively. Rwanda has the highest levels of antimalarial drug resistance in Africa. We correlated the efficacy of chlorproguanil-dapsone plus artesunate (CPG-DDS+A) and amodiaquine plus sulfadoxine-pyrimethamine (AQ+SP) in children with uncomplicated malaria caused by Plasmodium falciparum parasites with pfdhfr and pfdhps mutations, which are known to confer reduced drug susceptibility, in two areas of Rwanda. In the eastern province, where the cure rates were low, over 75% of isolates had three or more pfdhfr mutations and two or three pfdhps mutations and 11% had the pfdhfr 164-Leu polymorphism. In the western province, where the cure rates were significantly higher (P < 0.001), the prevalence of multiple resistance mutations was lower and the pfdhfr I164L polymorphism was not found. The risk of treatment failure following the administration of AQ+SP more than doubled for each additional pfdhfr resistance mutation (odds ratio [OR] = 2.4; 95% confidence interval [CI] = 1.01 to 5.55; P = 0.048) and each pfdhps mutation (OR = 2.1; 95% CI = 1.21 to 3.54; P = 0.008). The risk of failure following CPG-DDS+A treatment was 2.2 times higher (95% CI = 1.34 to 3.7) for each additional pfdhfr mutation, whereas there was no association with mutations in the pfdhps gene (P = 0.13). The pfdhfr 164-Leu polymorphism is prevalent in eastern Rwanda. Antimalarial treatments with currently available antifol-sulfa combinations are no longer effective in Rwanda because of high-level resistance.
Karema
Corine
C
National Malaria Control Program, Kigali, Rwanda.
Imwong
Mallika
M
Fanello
Caterina I
CI
Stepniewska
Kasia
K
Uwimana
Aline
A
Nakeesathit
Supatchara
S
Dondorp
Arjen
A
Day
Nicholas P
NP
White
Nicholas J
NJ
D000704:Analysis of Variance; D000962:Antimalarials / Q000494:pharmacology* / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D004338:Drug Combinations; D004351:Drug Resistance; D005493:Folic Acid Antagonists / Q000494:pharmacology* / Q000627:therapeutic use*; D005787:Gene Frequency; D017125:Genes, Protozoan / Q000235:genetics; D006239:Haplotypes; D006801:Humans; D007223:Infant; D016778:Malaria, Falciparum / Q000188:drug therapy* / Q000453:epidemiology / Q000469:parasitology*; D009154:Mutation / Q000235:genetics; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000235:genetics; D011110:Polymorphism, Genetic / Q000235:genetics; D011739:Pyrimethamine / Q000494:pharmacology / Q000627:therapeutic use; D012432:Rwanda / Q000453:epidemiology; D013413:Sulfadoxine / Q000494:pharmacology / Q000627:therapeutic use; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics / Q000378:metabolism
D000962:Antimalarials; D004338:Drug Combinations; D005493:Folic Acid Antagonists; C001205:fanasil, pyrimethamine drug combination; D013413:Sulfadoxine; D013762:Tetrahydrofolate Dehydrogenase; D011739:Pyrimethamine