Impact of Intermittent Preventive Treatment During Pregnancy on Plasmodium falciparum Drug Resistance-Mediating Polymorphisms in Uganda

Abstract

Background: In a recent trial of intermittent preventive treatment in pregnancy (IPTp) in Uganda, dihydroartemisinin-piperaquine (DP) was superior to sulfadoxine-pyrimethamine (SP) in preventing maternal and placental malaria.

Methods: We compared genotypes using sequencing, fluorescent microsphere, and quantitative polymerase chain reaction assays at loci associated with drug resistance in Plasmodium falciparum isolated from subjects receiving DP or SP.

Results: Considering aminoquinoline resistance, DP was associated with increased prevalences of mutations at pfmdr1 N86Y, pfmdr1 Y184F, and pfcrt K76T compared to SP (64.6% vs 27.4%, P < .001; 93.9% vs 59.2%, P < .001; and 87.7% vs 75.4%, P = .03, respectively). Increasing plasma piperaquine concentration at the time of parasitemia was associated with increasing pfmdr1 86Y prevalence; no infections with the N86 genotype occurred with piperaquine >2.75 ng/mL. pfkelch13 propeller domain polymorphisms previously associated with artemisinin resistance were not identified. Recently identified markers of piperaquine resistance were uncommon and not associated with DP. Considering antifolate resistance, SP was associated with increased prevalence of a 5-mutation haplotype (pfdhfr 51I, 59R, and 108N; pfdhps 437G and 581G) compared to DP (90.8% vs 60.0%, P = .001).

Conclusions: IPTp selected for genotypes associated with decreased sensitivity to treatment regimens, but genotypes associated with clinically relevant DP resistance in Asia have not emerged in Uganda.

Keywords: IPT; P. falciparum; dihydroartemisinin-piperaquine; drug resistance; sulfadoxine-pyrimethamine.

© The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

Figures

Figure 1.

Selection of samples for inclusion in the study. Abbreviations: DP, dihydroartemisinin-piperaquine; DP4w, dihydroartemisinin-piperaquine every 4 weeks; DP8w, dihydroartemisinin-piperaquine every 8 weeks; Pf, Plasmodium falciparum parasitemia; SP, sulfadoxine-pyrimethamine.

Figure 2.

Prevalence of wild-type, mixed, or mutant alleles at Plasmodium falciparum loci of interest in parasitemic samples collected from patients before intermittent preventive treatment in pregnancy (IPTp) treatment was initiated (None), in patients receiving sulfadoxine-pyrimethamine (SP) as IPTp, and in patients receiving dihydroartemisinin-piperaquine (DP) as IPTp.

Figure 3.

Impact of dosing frequency and recent use of dihydroartemisinin-piperaquine (DP) on the prevalence of wild-type, mixed, or mutant alleles at Plasmodium falciparum loci of interest in parasitemic samples. A, Allele prevalences in parasites from patients receiving DP every 8 weeks (DP8w) or every 4 weeks (DP4w). B, Allele prevalences in parasites from patients who received DP 29–56 days or 4–28 days before parasitemic episodes.

Figure 4.

Generalized linear models representing the predicted prevalence of mutant infections with increasing plasma piperaquine concentrations. Each dot represents the genotype of a single sample (top: mutant and mixed infections; bottom: pure wild-type infections). Blue curves represent estimated prevalence of mutant alleles. Gray-shaded areas indicate 95% confidence intervals.