There was no significant difference (P = 0.41) in blood Hb concentration in participants with or without asymptomatic malaria, with mean concentrations of 11.9 g/dL (95% CI 11.3–12.3) and 12.0 g/dL (95% CI 12.1–12.4), respectively, nor for participants at each of the three communes (S2 Table in S1 Appendix). This evidence concerns the gene GSTM1 and malaria.