Efficacy of Artesunate-Amodiaquine and Artemether-Lumefantrine for Uncomplicated Plasmodium Falciparum Malaria in Madagascar, 2018

Background: Since 2005, artemisinin-based combination therapy (ACT) has been recommended to treat uncomplicated Plasmodium falciparum malaria in Madagascar. Artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL) are the first- and second-line treatments, respectively. A therapeutic efficacy study was conducted to assess ACT efficacy and molecular markers of antimalarial resistance. Methods: Children aged six months through 14 years with uncomplicated P. falciparum malaria and a parasitemia of 1,000—100,000 parasites/µl determined by microscopy were enrolled from May—September 2018 in a 28-day in vivo trial using the 2009 World Health Organization protocol for monitoring antimalarial efficacy. Participants from two communes, Ankazomborona (tropical, northwest) and Matanga (equatorial, southeast), were randomly assigned to ASAQ or AL arms. PCR correction was achieved by genotyping seven neutral microsatellites in paired pre- and post-treatment samples. Genotyping assays for molecular markers of resistance in the pfk13 , pfcrt , and pfmdr1 genes were conducted. Results: Of 344 patients enrolled, 164/170 (96%) receiving ASAQ and 170/174 (98%) receiving AL completed the study. For ASAQ, the day-28 cumulative PCR-uncorrected efficacy was 100% (95% CI 100–100) and 95% (95% CI 91–100) for Ankazomborona and Matanga, respectively; for AL, it was 99% (95% CI 97–100) in Ankazomborona and 84% (95% CI 76–92) in Matanga. The day-28 cumulative PCR-corrected efficacy for ASAQ was 100% (95% CI 100–100) and 97% (95% CI 94–100%) for Ankazomborona and Matanga, respectively; for AL, it was 100% (95% CI 99–100) in Ankazomborona and 96% (95% CI 91–100) in Matanga. Of 83 successfully sequenced samples for pfk13 , no mutations associated with artemisinin resistance were observed. A majority of successfully sequenced samples for pfmdr1 carried either the NFD or NYD haplotypes corresponding to codons 86, 184, and 1246. Of 82 successfully sequenced samples for pfcrt , all were wild type at codons 72–76. Conclusion: PCR-corrected analysis indicated that ASAQ and AL have therapeutic efficacies above the 90% WHO acceptable cut-off. We did not observe any genetic evidence of resistance to artemisinin, consistent with the clinical outcome data. However, the most common pfmdr1 haplotypes were NYD and NFD, previously associated with tolerance to lumefantrine.