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Background  Malaria in Yemen is mainly caused by  Plasmodium falciparum  and 25 % of the population is at high risk. Sulfadoxine–pyrimethamine (SP) had been used as monotherapy against  P. falciparum . Emergence of chloroquine resistance led to the shift in anti-malarial treatment policy in Yemen to artemisinin-based combination therapy, that is artesunate (AS) plus SP as first-line therapy for uncomplicated malaria and artemether–lumefantrine as second-line treatment. This study aimed to screen mutations in the dihydrofolate reductase ( dhfr ) and dihydropteroate synthetase ( dhps ) genes associated with SP resistance among  P. falciparum  population in Hadhramout governorate, Yemen.    Methods  Genomic DNA was extracted from dried blood spots of 137  P. falciparum  isolates collected from a community-based study. DNA was amplified using nested polymerase chain reaction (PCR) and subsequently sequenced for  Pfdhfr  and  Pfdhps  genes. Sequences were analysed for mutations in  Pfdhfr  gene codons 51, 59, 108, and 164 and in  Pfdhps  gene codons 436, 437, and 540.    Results  A total of 128 and 114  P. falciparum  isolates were successfully sequenced for  Pfdhfr  and  Pfdhps  genes, respectively. Each  Pfdhfr  mutant allele ( I   51   and  N   108  ) in  P. falciparum  population had a frequency of 84 %.  Pfdhfr  R   59   mutant allele was detected in one isolate. Mutation at codon 437 ( G   437  ) in the  Pfdhps  gene was detected in 44.7 % of  falciparum  malaria isolates. Frequencies of  Pfdhfr  double mutant genotype (  I    51  C 59   N    108  I 164 ) and  Pfdhfr / Pfdhps  triple mutant genotype (  I    51  C 59   N   108 I 164 -S 436   G   437 K 540 ) were 82.8 and 39.3 %, respectively. One isolate harboured  Pfdhfr  triple mutant genotype (  I    51  ,   R    59  ,   N    108  , I 164 ) and  Pfdhfr / Pfdhps  quadruple mutant genotype (  I   51   R   59   N   108 I 164 -S 436   G   437 K 540 ).    Conclusion  High frequencies of  Pfdhfr  and  Pfdhps  mutant alleles and genotypes in  P. falciparum  population in Hadhramout, Yemen, highlight the risk of developing resistance for SP, the partner drug of AS, which subsequently will expose the parasite to AS monotherapy increasing then the potential of the emergence of AS resistance. Study findings necessitate the continuous monitoring of the efficacy of the national anti-malarial drugs policy in Yemen. In addition, monitoring SP efficacy using molecular markers that has shown to be a practical and informative method for monitoring the partner drug of AS.

malaria journal

Frequencies distribution of dihydrofolate reductase and dihydropteroate synthetase mutant alleles associated with sulfadoxine–pyrimethamine resistance in Plasmodium falciparum population from Hadhramout Governorate, Yemen