title: A thirteen-year analysis of Plasmodium falciparum populations reveals high conservation of the mutant pfcrt haplotype despite the withdrawal of chloroquine from national treatment guidelines in Gabon.
abstract: BACKGROUND
  Chloroquine resistance (CR) decreased after the removal of chloroquine from national treatment guidelines in Malawi, Kenia and Tanzania. In this investigation the prevalence of the chloroquine resistance (CQR) conferring mutant pfcrt allele and its associated chromosomal haplotype were determined before and after the change in Gabonese national treatment guidelines from chloroquine (CQ) to artesunate plus amodiaquine (AQ) in 2003.
  
  
  METHODS
  The prevalence of the wild type pfcrt allele was assessed in 144 isolates from the years 2005 - 07 by PCR fragment restriction digest and direct sequencing. For haplotype analysis of the chromosomal regions flanking the pfcrt locus, microsatellite analysis was done on a total of 145 isolates obtained in 1995/96 (43 isolates), 2002 (47 isolates) and 2005 - 07 (55 isolates).
  
  
  RESULTS
  The prevalence of the mutant pfcrt allele decreased from 100% in the years 1995/96 and 2002 to 97% in 2005 - 07. Haplotype analysis showed that in 1995/96 79% of the isolates carried the same microsatellite alleles in a chromosomal fragment spanning 39 kb surrounding the pfcrt locus. In 2002 and 2005 - 07 the prevalence of this haplotype was 62% and 58%, respectively. Pfcrt haplotype analysis showed that all wild type alleles were CVMNK.
  
  
  CONCLUSIONS
  Four years after the withdrawal of CQ from national treatment guidelines the prevalence of the mutant pfcrt allele remains at 97%. The data suggest that the combination of artesunate plus AQ may result in continued selection for the mutant pfcrt haplotype even after discontinuance of CQ usage.
authors: Institute of Tropical Medicine, University of Tübingen, Wilhelmstr.27, 72074 Tübingen, Germany. Matthias.frank@uni-tuebingen.de
authors: Matthias
authors: M
authors: Frank
authors: Nicola
authors: N
authors: Lehners
authors: Pembe I
authors: PI
authors: Mayengue
authors: Julian
authors: J
authors: Gabor
authors: Matthias
authors: M
authors: Dal-Bianco
authors: David U
authors: DU
authors: Kombila
authors: Ghyslain Mombo
authors: GM
authors: Ngoma
authors: Christian
authors: C
authors: Supan
authors: Bertrand
authors: B
authors: Lell
authors: Francine
authors: F
authors: Ntoumi
authors: Martin P
authors: MP
authors: Grobusch
authors: Klaus
authors: K
authors: Dietz
authors: Peter G
authors: PG
authors: Kremsner
mesh_terms: D000655:Amodiaquine / Q000627:therapeutic use*; D000962:Antimalarials / Q000627:therapeutic use*; D037621:Artemisinins / Q000627:therapeutic use*; D002738:Chloroquine / Q000627:therapeutic use*; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D004338:Drug Combinations; D004351:Drug Resistance; D005681:Gabon; D006239:Haplotypes; D006291:Health Policy; D006801:Humans; D008288:Malaria / Q000188:drug therapy* / Q000469:parasitology; D026901:Membrane Transport Proteins / Q000235:genetics*; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D015800:Protozoan Proteins / Q000235:genetics*; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D000962:Antimalarials; D037621:Artemisinins; D016054:DNA, Protozoan; D004338:Drug Combinations; D026901:Membrane Transport Proteins; C416369:PfCRT protein, Plasmodium falciparum; D015800:Protozoan Proteins; C515299:amodiaquine, artesunate drug combination; D000655:Amodiaquine; D002738:Chloroquine