Occurrence of multiple chloroquine-resistant Pfcrt haplotypes and emergence of the S(agt)VMNT type in Cameroonian Plasmodium falciparum.

OBJECTIVES The main objective of this study was to unravel the distribution of different Pfcrt genotypes in the central, littoral, eastern and southern regions of Cameroon and also in locations bordering Gabon and Equatorial Guinea. This is because (i) the chloroquine-resistant malaria parasite Plasmodium falciparum shows a wide occurrence in Cameroon, (ii) mutations in the 72nd to 76th amino acid positions of the Pfcrt gene are known to confer resistance to chloroquine, and (iii) only a single chloroquine-resistant haplotype (C72V73I74E75T76) has so far been reported in Cameroon. METHODS We followed a molecular approach with DNA sequencing of the second exon of the Pfcrt gene to identify single nucleotide polymorphisms in 180 P. falciparum field isolates sampled in five different locations in Cameroon. RESULTS The chloroquine-resistant Pfcrt CVIET haplotype was most abundant, followed by the wild-type CVMNK haplotype. Five hitherto unreported chloroquine-resistant Pfcrt haplotypes were detected for the first time in Cameroonian P. falciparum, including the surprise appearance of the S(agt)VMNT haplotype. CONCLUSIONS The high observed haplotype diversity of the chloroquine-resistant Pfcrt gene and the appearance of the S(agt)VMNT haplotype are daunting and can be attributed to drug pressure and/or the misuse of chloroquine and/or amodiaquine in Cameroon.