Prevalence of Plasmodium falciparum chloroquine resistant gene markers, pfcrt-76 and pfmdr1-86, eight years after cessation of chloroquine use in Mwea, Kenya

Abstract

The prevalence of T76 and Y86 Plasmodium falciparum molecular markers for chloroquine (CQ) resistance in the Pfcrt and Pfmdr1 genes were investigated by PCR-RFLP and dot blot analysis in samples (50 for Pfcrt and 51 for Pfmdr1) collected in May 2005, eight years after chloroquine (CQ) cessation. Results: Our findings show that 94% of field isolates from this site still harbor T76 mutation in Pfcrt while 6% have the wild type allele K76 [T test, P=0.04058 (1997 versus 2005)]. Dot blot analysis revealed that most of the isolates had MET polymorphism at position 74, 75 and 76 wild type allele of the Pfcrt gene. When Pfmdr1-86 was analyzed by dot blot, 6% of the isolates had wild type allele N86, 73% had mutant allele Y86, and 21% had both N and Y [T test, P=0.04058 (1997 versus 2005)]). Conclusions: Dot blot hybridization was found to be more sensitive and specific than PCR-RFLP. The study showed a moderate reversal to sensitivity by the P. falciparum population in the study site compared to the situation before CQ cessation