Relationship between red blood cell polymorphisms and effectiveness of seasonal malaria chemoprevention in 2020 in Dangassa, Mali.

Treatment failure with amodiaquine was reported in Dangassa, where red blood cell (RBC) polymorphisms are found and seasonal malaria chemoprevention (SMC) is underway. Here, we aimed at assessing the influence of RBC polymorphisms on SMC effectiveness. This was a secondary analysis of data from a study conducted in Dangassa. Children aged 5 to 14 years enrolled in an open randomized study were assigned either to receive SMC (intervention arm) or not (control arm). SMC was implemented from July to November. For all children, hemoglobin type and blood group were determined at enrolment in July, and parasitemia and hemoglobin level were monthly monitored by finger-prick. Overall, 166 children were enrolled among which 82 (49.40%) in the control arm and 84 (50.60%) in the SMC arm. The prevalence of HbAS was 10.24% (17/166) with 12.20% in the control and 8.33% in the SMC arm. O group was the most common overall (45%) and in the SMC arm (54%), but the control arm had more B (39.02%) than O (36.59%). In the SMC arm, no case of Plasmodium infection and malaria disease was observed in the 7 HbAS children while in Non-HbAS children, peaks of infection and disease prevalence were respectively observed in October (24.66%) and November (7.14%). For the SMC arm, in group O and Non-group O, Plasmodium infection cases were observed from August to December. Plasmodium infection and malaria disease were more frequently observed in HbAS children in the control arm than in the SMC arm. Further studies are needed to assess factors associated with the asymptomatic carriage of parasites during SMC in Dangassa. NCT04149106.