Directional selection at the pfmdr1, pfcrt, pfubp1, and pfap2mu loci of Plasmodium falciparum in Kenyan children treated with ACT

J Infect Dis. 2014 Dec 15;210(12):2001-8. doi: 10.1093/infdis/jiu358. Epub 2014 Jul 3.


Background: The efficacy of artemisinin-based combination therapy (ACT) for Plasmodium falciparum malaria may be threatened by parasites with reduced responsiveness to artemisinins. Among 298 ACT-treated children from Mbita, Kenya, submicroscopic persistence of P. falciparum on day 3 posttreatment was associated with subsequent microscopically detected parasitemia at days 28 or 42.

Methods: DNA sequences of resistance-associated parasite loci pfcrt, pfmdr1, pfubp1, and pfap2mu were determined in the Mbita cohort before treatment, on days 2 and 3 after initiation of treatment, and on the day of treatment failure.

Results: Parasites surviving ACT on day 2 or day 3 posttreatment were significantly more likely than the baseline population to carry the wild-type haplotypes of pfcrt (CVMNK at codons 72-76; P < .001) and pfmdr1 (NFD at codons 86, 184, 1246; P < .001). In contrast, variant alleles of the novel candidate resistance genes pfap2mu (S160N/T; P = .006) and pfubp-1 (E1528D; P < .001) were significantly more prevalent posttreatment. No genetic similarities were found to artemisinin-tolerant parasites recently described in Cambodia.

Conclusions: Among treated children in western Kenya, certain P. falciparum genotypes defined at pfcrt, pfmdr1, pfap2mu, and pfubp1 more often survive ACT at the submicroscopic level, and contribute to onward transmission and subsequent patent recrudescence.

Keywords: artemisinin; drug resistance; genetics; malaria.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antimalarials / therapeutic use*
  • Artemisinins / therapeutic use*
  • Cambodia
  • Child
  • Child, Preschool
  • Drug Resistance
  • Drug Therapy, Combination
  • Female
  • Genotype
  • Humans
  • Infant
  • Kenya
  • Malaria, Falciparum / drug therapy*
  • Male
  • Membrane Transport Proteins / genetics*
  • Multidrug Resistance-Associated Proteins / genetics*
  • Plasmodium falciparum / genetics*
  • Plasmodium falciparum / isolation & purification
  • Protozoan Proteins / genetics*
  • Selection, Genetic*


  • Antimalarials
  • Artemisinins
  • Mdr1 protein, Plasmodium falciparum
  • Membrane Transport Proteins
  • Multidrug Resistance-Associated Proteins
  • PfCRT protein, Plasmodium falciparum
  • Protozoan Proteins
  • artemisinin