Hb concentration was higher in the intervention group than in the control group at the end of the malaria transmission season (mean Hb 11.01 g/dl [95% CI 10.94–11.08 g/dl] versus a mean of 10.35 g/dl [95% CI 10.27–0.42 g/dl]) (p<0.001). This evidence concerns the gene GSTM1 and malaria.