Occurrence of septuple and elevated Pfdhfr-Pfdhps quintuple mutations in a general population threatens the use of sulfadoxine-pyrimethamine for malaria prevention during pregnancy in eastern-coast of Tanzania

BackgroundPlasmodium falciparumdihydrofolate reductase (Pfdhfr) and dihydropteroate synthetase (Pfdhps) mutations compromise the effectiveness of sulfadoxine-pyrimethamine (SP) for treatment of uncomplicated malaria, and are likely to impair the efficiency of intermittent preventive treatment during pregnancy (IPTp). This study was conducted to determine the level ofPfdhfr-Pfdhpsmutations, a decade since SP was limited for IPTp use in pregnant women in Tanzania.MethodsP. falciparumgenomic DNA was extracted from dried blood spots prepared from a finger prick. Extracted DNA were sequenced using a single MiSeq lane by combining all PCR products. Genotyping ofPfdhfrandPfdhpsmutations were done using bcftools whereas custom scripts were used to filter and translate genotypes into SP resistance haplotypes.ResultsThePfdhfrwas analyzed from 445 samples, the wild type (WT)Pfdhfrhaplotype NCSI was detected in 6 (1.3%) samples. TriplePfdhfrIRNI (mutations are bolded and underlined) haplotype was dominant, contributing to 84% (number [n] = 374) of haplotypes while 446 samples were studied forPfdhps, WT forPfdhps(SAKAA) was found in 6.7% (n = 30) in samples. DoublePfdhpshaplotype (SGEAA) accounted for 83% of all mutations atPfdhpsgene. Of 447Pfdhfr-Pfdhpscombined genotypes, only 0.9% (n = 4) samples contained WT gene (SAKAA-NCSI). Quintuple (five) mutations, SGEAA-IRNI accounted for 71.4% (n = 319) whereas 0.2% (n = 1) had septuple (seven) mutations (AGKGS-IRNI). The overall prevalence ofPfdhfrK540E was 90.4% (n = 396) whilePfdhpsA581G was 1.1% (n = 5).ConclusionsThis study found high prevalence ofPfdhfr–Pfdhpsquintuple and presence of septuple mutations. Mutations atPfdhfrK540E andPfdhpsA581G, major predictors for IPTp-SP failure were within the recommended WHO range. Abandonment of IPTp-SP is recommended in settings where thePfdhfrK540E prevalence is > 95% andPfdhpsA581G is > 10% as SP is likely to be not effective. Nonetheless, saturation inPfdhfrandPfdhpshaplotypes is alarming, a search for alternative antimalarial drug for IPTp in the study area is recommended.