title: Chloroquine sensitivity: diminished prevalence of chloroquine-resistant gene marker pfcrt-76 13 years after cessation of chloroquine use in Msambweni, Kenya.
abstract: BACKGROUND
  Plasmodium falciparum resistance to chloroquine (CQ) denied healthcare providers access to a cheap and effective anti-malarial drug. Resistance has been proven to be due to point mutations on the parasite's pfcrt gene, particularly on codon 76, resulting in an amino acid change from lysine to threonine. This study sought to determine the prevalence of the pfcrt K76T mutation 13 years after CQ cessation in Msambweni, Kenya.
  
  
  METHODS
  Finger-prick whole blood was collected on 3MM Whatman(®) filter paper from 99 falciparum malaria patients. Parasite DNA was extracted via the Chelex method from individual blood spots and used as template in nested PCR amplification of pfcrt. Apo1 restriction enzyme was used to digest the amplified DNA to identify the samples as wild type or sensitive at codon 76. Prevalence figures of the mutant pfcrt 76T gene were calculated by dividing the number of samples bearing the mutant gene with the total number of samples multiplied by 100 %. Chi square tests were used to test the significance of the findings against previous prevalence figures.
  
  
  RESULTS
  Out of 99 clinical samples collected in 2013, prevalence of the mutant pfcrt 76T gene stood at 41 %.
  
  
  CONCLUSIONS
  The results indicate a significant [χ(2) test, P ≤ 0.05 (2006 vs 2013)] reversal to sensitivity by the P. falciparum population in the study site compared to the situation reported in 2006 at the same study site. This could primarily be driven by diminished use of CQ in the study area in line with the official policy. Studies to establish prevalence of the pfcrt 76T gene could be expanded countrywide to establish the CQ sensitivity status and predict a date when CQ may be re-introduced as part of malaria chemotherapy.
authors: Institute of Tropical Medicine and Infectious Diseases (ITROMID), PO Box 54840-00200, Nairobi, Kenya. chege.william@gmail.com.|Kenya Medical Research Institute, Centre for Biotechnology Research and Development (KEMRI, CBRD), PO Box 54840-00200, Nairobi, Kenya. chege.william@gmail.com.
authors: William Chege
authors: WC
authors: Kiarie
authors: School of Health Sciences, Kirinyaga University College (Constituent College of JKUAT), P.O. Box 143-10300, Kerugoya, Kenya. lauranyawira@yahoo.com.
authors: Laura
authors: L
authors: Wangai
authors: Kenya Medical Research Institute, Centre for Biotechnology Research and Development (KEMRI, CBRD), PO Box 54840-00200, Nairobi, Kenya. elelo@kemri.org.
authors: Eric
authors: E
authors: Agola
authors: Kenya Medical Research Institute, Centre for Biotechnology Research and Development (KEMRI, CBRD), PO Box 54840-00200, Nairobi, Kenya. fkimani@kemri.org.
authors: Francis T
authors: FT
authors: Kimani
authors: Kenya Medical Research Institute, Centre for Biotechnology Research and Development (KEMRI, CBRD), PO Box 54840-00200, Nairobi, Kenya. charityhungu@gmail.com.
authors: Charity
authors: C
authors: Hungu
mesh_terms: D000962:Antimalarials / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D002738:Chloroquine / Q000494:pharmacology*; D003062:Codon; D004351:Drug Resistance / Q000187:drug effects / Q000235:genetics; D005260:Female; D005819:Genetic Markers / Q000235:genetics; D006801:Humans; D007630:Kenya / Q000453:epidemiology; D016778:Malaria, Falciparum / Q000453:epidemiology / Q000469:parasitology*; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics*; D017720:Molecular Epidemiology; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000235:genetics*; D015995:Prevalence; D015800:Protozoan Proteins / Q000235:genetics*
chemical_list: D000962:Antimalarials; D003062:Codon; D005819:Genetic Markers; D026901:Membrane Transport Proteins; C416369:PfCRT protein, Plasmodium falciparum; D015800:Protozoan Proteins; D002738:Chloroquine