Prevalence of pfdhfr-pfdhps Sextuple and Gametocyte-Associated Quintuple Sulfadoxine-Pyrimethamine Resistance Mutations in Plasmodium falciparum Isolates from Pregnant Women in Mozambique

Intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) remains the main strategy to prevent malaria in pregnancy. However, continued drug pressure may also contribute to the emergence of resistant parasites and impact the gametocyte carriage and subsequent infectiousness. Pregnant women are thought to be a potential reservoir for malaria transmission due to the increased carriage of gametocytes following long-lasting infections. We used molecular methods to examine 100 Plasmodium falciparum (P. falciparum) isolates collected from Mozambican women at delivery in 2014-15 to determine sulfadoxine-pyrimethamine (SP) resistance polymorphisms in P. falciparum dihydrofolate reductase (pfdhfr) and dihydropteroate synthetase (pfdhps) genes, as well as the presence of gametocytes by RT-qPCR. Overall, 54% and 7% of parasites harbored quintuple and sextuple pfdhfr/pfdhps mutant haplotypes, respectively. Gametocytes were detected in 34% of isolates. Gametocyte carriage was significantly associated with quintuple mutant infections (AOR = 7.5, p = 0.001), which accounted for 80% of infections with detectable gametocytes. Results indicate the relevance of ongoing surveillance of SP resistance in Mozambique to guide future evaluation of alternative intermittent preventive treatment in pregnancy (IPTp) approaches as resistance levels evolve and anticipate potential implications for parasite transmission and maternal-fetal health.