Assessing of Pfdhps Gene of Sulfadoxine after Five Years of Seasonal Malaria Chemoprevention Implementation at Two Rural Sites in Mali: The Quantitative Method

Author(s): : Hamma Maiga, Robert Morrison, Issaka Sagara, Jennifer Hume, Sara Healy, Mahamadoun H. Assadou, Abdoulaye Katile, Amatigue Zeguime, Jillian Neal, Irfan Zaidi and Patrick E. Duffy

Seasonal malaria chemoprevention (SMC) aims to prevent malaria in children under 5-year of age and this strategy was implemented in Mali since 2012. Mass administration of sulfadoxine-pyrimethamine plus amodiaquine (SPAQ) could potentially generate drug-resistant Plasmodium falciparum parasites after several years. In this study, we investigated the mean fraction of resistance gene markers in the drug target of sulfadoxine Pfdhps among children and adults after 5 years of SMC implementation at two rural sites in Mali. From June to December 2019 at Doneguebougou and Bancoumana, data were collected from children under 5 years of age who received SMC as well as older individuals did not receive SMC. In Doneguebougou specifically, participants were 5 years and older received an investigational malaria transmission-blocking vaccine (Pfs230D1-EPA/AS01) or a comparator vaccine, and all children received artemether-lumefantrine before vaccination. Genomic DNA was extracted from filter paper blood spots and whole blood, then nested PCR was used to amplify the Pfdhps gene. Sanger sequencing of resistance loci fragments and deconvolution of chromatograms were used to quantify Pfdhps molecular marker variants and genotypes I431V, S436F/A, A437G, K540E, A581G and A613S/T. A total of 456 children and adults were evaluated in Doneguebougou (n=202) and Bancoumana (n=254). The mean fraction of resistance markers was significantly different between smc-group versus non-smc-group in Doneguebougou, but not in Bancoumana for Pfdhps at codons 431V and 613S/T. Highest mean fraction was found with the Pfdhps single mutant 436A/F and 437G in smc-group as well as in non-smc-group at both sites. Pfdhps 540E was not found in the Doneguebougou smc-group. There was no difference in the mean fraction of Pfdhps at all codons by age category (1-4years, 5-8yrs, 9-18yrs and adults), when data from both sites were combined. The mean fraction of Pfdhps 540E and 581G were low after five years of SMC implementation, suggesting that sulfadoxine-pyrimethamine remains an effective antimalarial drug in these two sites in Mali. Otherwise, sulfadoxine resistance molecular markers in Bancoumana were as high or higher in the non-smc-group as smc-group