Hb level at enrolment was negatively associated with Pf- and Pv-molFOB (P. vivax: IRRPQ arm=0.85 [0.72–1.01], p=0.063; IRRPlacebo arm=0.91 [0.85–0.99], p=0.025; P. falciparum: IRR = 0.85 [0.75–0.97], p=0.013), suggesting anaemia in individuals continuously exposed to blood-stage infections. This evidence concerns the gene GSTM1 and anemia (phenotype).