Variouspfcrtandpfmdr1Genotypes of Plasmodium falciparum Cocirculate with P. malariae, P. ovale spp., and P. vivax in Northern Angola

Abstract

ABSTRACTArtemisinin-based combination therapy for malaria has become widely available across Africa. Populations ofPlasmodium falciparumthat were previously dominated by chloroquine (CQ)-resistant genotypes are now under different drug selection pressures.P. malariae,P. ovale curtisi, andP. ovale wallikeriare sympatric withP. falciparumacross the continent and are frequently present as coinfections. The prevalence of humanPlasmodiumspecies was determined by PCR using DNA from blood spots collected during a cross-sectional survey in northern Angola.P. falciparumwas genotyped at resistance-associated loci inpfcrtandpfmdr1by real-time PCR or by direct sequencing of amplicons. Of the 3,316 samples collected, 541 (16.3%) containedPlasmodiumspecies infections; 477 (88.2%) of these wereP. falciparumalone, 6.5% wereP. falciparumandP. malariaetogether, and 1.1% wereP. vivaxalone. The majority of the remainder (3.7%) harboredP. ovale curtisiorP. ovale wallikerialone or in combination with other species. Of 430P. falciparumisolates genotyped forpfcrt, 61.6% carried the wild-type allele CVMNK at codons 72 to 76, either alone or in combination with the resistant allele CVIET. No otherpfcrtallele was found. Wild-type alleles dominated at codons 86, 184, 1034, 1042, and 1246 of thepfmdr1locus among the sequenced isolates. In contrast to previous studies,P. falciparumin the study area comprises an approximately equal mix of genotypes associated with CQ sensitivity and with CQ resistance, suggesting either lower drug pressure due to poor access to treatment in rural areas or a rapid impact of the policy change away from the use of standard monotherapies.