Pregnant women as a sentinel population for genomic surveillance of malaria in the Democratic Republic of Congo

Genomic surveillance is a valuable tool for detecting changes in the drug susceptibility of malaria parasites, allowing early modification of treatment strategies. However, implementation can be costly and problematic to set up in fragile and high-burden countries, especially when targeting cohorts of children. To address these challenges, we investigated whether in the Democratic Republic of Congo pregnant women attending antenatal care (ANC) services could act as a surrogate sentinel population. Between 2021 and 2023, we conducted a study in Kinshasa, targeting 4,001 pregnant women attending ANCs, and 2,794 children living in the same area. Blood samples from malaria-positive cases were genotyped using an amplicon sequencing platform, to allow comparisons of Plasmodium falciparum genomes between the two cohorts and estimations of drug-resistance mutations prevalence. Parasite populations sampled from the two cohorts exhibited highly similar allele frequencies at all tested loci, including drug resistance markers potentially under selection. Pregnant women did not have higher frequencies of sulphadoxine-pyrimethamine resistant haplotypes, which undermine preventive treatments, than children, and we did not find any kelch13 mutation at significant frequency. Although parasite densities were lower in adults, the complexity of infection was similar to that in children. There was no evidence of Plasmodium vivax infections in the study. A cohort of pregnant women produces highly similar results to those from children, allowing the implementation of simple and efficient genomic surveillance systems integrated into routine ANC activities, while benefitting women with diagnosis and treatment. ClinicalTrials.gov Identifier: NCT05072613.