Molecular markers of sulfadoxine-pyrimethamine resistant malaria prior to intermittent preventive treatment among pregnancies in Makurdi, Nigeria

Abstract

Molecular markers of sulfadoxine-pyrimethamine (SP) resistance were monitored in pregnant women of mean age 28 ± 11years in Makurdi, Nigeria. A total of 82 Plasmodium falciparum malaria positive blood samples were obtained prior to commencement of intermittent preventive treatment with SP (IPTp-SP) during antenatal visits. Of the 82 samples, 71 were successfully genotyped at the dihydrofolate reductase (dhfr) loci
51, 59, 108 and 164; and dihydropteroate synthase (dhps) loci 436, 437, and 540. The genotyping was accomplished by means of polymerase chain reaction, and restriction fragment length polymorphisms. The aim was to determine the percentage frequencies of P. falciparum single nucleotide polymorphisms (SNPs) associated with resistance to SP in vivo. The results show that both the dhfr and dhps genes each produced 5 different haplotypes with varying percentage frequencies. All genotyped gene loci had SNPs except dhfr 164 and dhps 540. Haplotype combination of dhfr/dhps alleles yielded 15 different genotypes of P. falciparum parasites. The combined frequencies of triple/quadruple mutant haplotypes associated with in vivo SP resistance was 35.21%, but was significantly lower than single/double mutant haplotypes not associated with SP resistance (χ² = 6.21, df = 1, p = 0.01). These results suggest a possible rise in in vivo SP resistance during IPT_P-SP. There is a need for continuous monitoring of SP efficacy, for effective intermittent preventive treatment with the drug in the area.

Keywords: Malaria, antimalarial drug resistance, single nucleotide polymorphisms, haplotype.