PA-382 Trends in sulfadoxine-pyrimethamine resistance molecular markers among plasmodium falciparum isolates before and after adopting seasonal malaria chemoprevention in Nanoro, Burkina Faso

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Background Despite various efforts to control malaria among children, the disease remains a leading cause of morbidity and mortality worldwide. In the Sahel region, including Burkina Faso, seasonal malaria chemoprevention (SMC) using Sulfadoxine-Pyrimethamine (SP) and Amodiaquine has been implemented since 2014. However, introducing this new strategy may lead to the spread of Plasmodium falciparum resistance to SP. This study analyses the mutations in SP resistance genes, dihydrofolate reductase (Pfdhfr) and dihydropteroate synthase (Pfdhps) before and after adopting SMC in Burkina Faso.Methods Dried blood spots obtained from previous studies conducted in Nanoro from 2010 to 2020 were randomly selected. Out of this selection, 769 Plasmodium falciparum isolates were retained, with 299 collected between 2010–2012 before the SMC adoption and 470 collected between 2018–2020 after the SMC implementation in 2014. The Pfdhps and Pfdhfr genes were amplified using nested PCR, and mutations that confer resistance were identified by sequencing the resulting products.Results The prevalence of Pfdhfr triple mutations (CIRNI) increased from 44.4% before the adoption of SMC to 84.4% following its implementation (p<0.0001). There were no mutations at codon Pfdhps 540; those at Pfdhps 581 remained rare and were reported exclusively after the SMC implementation (2.8%). The prevalence of haplotypes observed for the Pfdhps gene did not differ significantly over time. However, the Pfdhps haplotype quadruple mutant VAAKGS recently reported in Nigeria was found only in 2020 (1.4%). The combined Pfdhfr/Pfdhps quadruple mutant IRN/AAKA was the most common and increased following SMC implementation (44.9% vs 16.5%; p<0.0001).Conclusion After the SMC implementation, the prevalence of Pyrimethamine resistance markers increased significantly, while no difference was observed for Sulfadoxine resistance markers. Nevertheless, the detection in 2020 of the emerging Pfdhps haplotypes highlights the need to monitor SP resistance continuously.Funding: PAMAFRICA/EDCTP

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