Molecular Surveillance of Drug Resistance Markers in Clinical Samples from Botswana.

Drug-resistant is a major threat to global malaria control and elimination efforts. In Botswana, a southern African country approaching malaria elimination, molecular data are not available. Parasites were assessed through pollymerase chain reaction (PCR) for confirmation of positive rapid diagnostic tests, multiplicity of infection (MOI), and drug resistance markers among isolates from clinical uncomplicated malaria cases collected at health facilities. Of 211 dried blood spot samples selected for the study, 186 (88.2%) were PCR positive for . The mean MOI based on genotyping was 2.3 and was not associated with age. A high prevalence of wild-type parasites for and was found, with a haplotype frequency (K76/N86) of 88.8% and 17.7% of the isolates having two copies of the gene. For , all the parasites carried the wild-type S769 allele. Sequencing showed no evidence of non-synonymous mutations associated with reduced artemisinin derivative sensitivity in the gene. In conclusion, we found that parasites in Botswana were mostly wild type for the drug resistance markers evaluated. Yet, there was a high rate of a molecular marker associated to reduced sensitivity to lumefantrine. Our results indicate the need for systematic drug efficacy surveillance to complement malaria elimination efforts.