Distribution of drug resistance genotypes in Plasmodium falciparum in an area of limited parasite diversity in Saudi Arabia.

Two hundred and three Plasmodium falciparum isolates from Jazan area, southwest Saudi Arabia, were typed for Pfcrt, Pfmdr1, dhps, and dhfr mutations associated with resistance to chloroquine, mefloquine, halofantrine, artemisinin, sulfadoxine-pyrimethamine, and the neutral polymorphic gene Pfg377. A large proportion (33%) of isolates harbored double mutant dhfr genotype (51I,59C,108N). However, only one isolate contained mutation dhps-437G. For Pfcrt, almost all examined isolates (163; 99%) harbored the mutant genotype (72C,73V,74I,75E,76T), whereas only 49 (31%) contained the mutant Pfmdr1 genotype (86Y,184F,1034S,1042N), 109 (66%) harbored the single mutant genotype (86N,184F,1034S,1042N), and no mutations were seen in codons 1034, 1042, and 1246. Nonetheless, three new single-nucleotide polymorphisms were detected at codons 182, 192, and 102. No differences were seen in distribution of drug resistance genes among Saudis and expatriates. There was a limited multiplicity (5%), mean number of clones (1.05), and two dominant multilocus genotypes among infected individuals in Jazan. A pattern consistent with limited cross-mating and recombination among local parasite was apparent.