The A581G Mutation in the Gene Encoding Plasmodium falciparum Dihydropteroate Synthetase Reduces the Effectiveness of Sulfadoxine-Pyrimethamine Preventive Therapy in Malawian Pregnant Women.
BACKGROUND: The A581 G: mutation in the gene encoding Plasmodium falciparum dihydropteroate synthase (dhps), in combination with the quintuple mutant involving mutations in both dhps and the gene encoding dihydrofolate reductase (dhfr), the so-called sextuple mutant, has been associated with increased placental inflammation and decreased infant birth weight among women receiving intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) during pregnancy. METHODS: Between 2009 and 2011, delivering women without human immunodeficiency virus infection were enrolled in an observational study of IPTp-SP effectiveness in Malawi. Parasites were detected by polymerase chain reaction (PCR); positive samples were sequenced to genotype the dhfr and dhps loci. The presence of K540 E: in dhps was used as a marker for the quintuple mutant. RESULTS: Samples from 1809 women were analyzed by PCR; 220 (12%) were positive for P. falciparum. A total of 202 specimens were genotyped at codon 581 of dhps; 17 (8.4%) harbored the sextuple mutant. The sextuple mutant was associated with higher risks of patent infection in peripheral blood (adjusted prevalence ratio [aPR], 2.76; 95% confidence interval [CI], 1.82-4.18) and placental blood (aPR 3.28; 95% CI, 1.88-5.78) and higher parasite densities. Recent SP use was not associated with increased parasite densities or placental pathology overall and among women with parasites carrying dhps A581 G: . CONCLUSIONS: IPTp-SP failed to inhibit parasite growth but did not exacerbate pathology among women infected with sextuple-mutant parasites. New interventions to prevent malaria during pregnancy are needed urgently.
Gutman, J; Kalilani, L; Taylor, S; Zhou, Z; Wiegand, RE; Thwai, KL; Mwandama, D; Khairallah, C; Madanitsa, M; Chaluluka, E; Dzinjalamala, F; Ali, D; Mathanga, DP; Skarbinski, J; Shi, YP; Meshnick, S; ter Kuile, FO
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