%0 Journal Article
%T Identification of pyrimethamine- and chloroquine-resistant Plasmodium falciparum in Africa between 1984 and 1998: genotyping of archive blood samples
%A Yumiko Saito-Nakano
%A Kazuyuki Tanabe
%A Toshihiro Mita
%J Malaria Journal
%D 2011
%I BioMed Central
%R 10.1186/1475-2875-10-388
%X Parasite DNA was extracted from P. falciparum-infected blood smears collected from travellers returning to Japan from Africa between 1984 and 1998. Genotypes of the dihydrofolate reductase gene (dhfr) and CQ-resistance transporter gene (pfcrt) were determined by polymerase chain reaction amplification and sequencing.Genotyping of dhfr and pfcrt was successful in 59 and 80 samples, respectively. One wild-type and seven mutant dhfr genotypes were identified. Three dhfr genotypes lacking the S108N mutation (NRSI, ICSI, IRSI; amino acids at positions 51, 59, 108, and 164 with mutations underlined) were highly prevalent before 1994 but reduced after 1995, accompanied by an increase in genotypes with the S108N mutation. The dhfr IRNI genotype was first identified in Nigeria in 1991 in the present samples, and its frequency gradually increased. However, two double mutants (ICNI and NRNI), the latter of which was exclusively found in West Africa, were more frequent than the IRNI genotype. Only two pfcrt genotypes were found, the wild-type and a Southeast Asian type (CVIET; amino acids at positions 72-76 with mutations underlined). The CVIET genotype was already present as early as 1984 in Tanzania and Nigeria, and appeared throughout Africa between 1984 and 1998.This study is the first to report the molecular identification of Pyr- and CQ-resistant genotypes of P. falciparum in Africa before 1990. Genotyping of dhfr and pfcrt using archive samples has revealed new aspects of the evolutionary history of Pyr- and CQ-resistant parasites in Africa.Drug resistance of Plasmodium falciparum, the most virulent human malaria parasite, is imposing a serious problem for the effective treatment of malaria in almost all endemic areas. Thus it is imperative to understand the geographical distribution and origin of the parasite's drug resistance. In Africa, clinical resistance of falciparum malaria to chloroquine (CQ) was first reported in the late 1970s [1,2]. In addition, while clinical
%K Plasmodium falciparum
%K Drug resistance
%K Chloroquine
%K pfcrt
%K Pyrimethamine
%K dhfr
%K Africa
%K Archive sample
%U http://www.malariajournal.com/content/10/1/388