Extrapolating the Hb data from the vivax-infected Cambodians and assuming similar Hb dynamics in patients with falciparum and vivax malaria [41], 0.38 mg/kg of PQ base (i.e. approximately half the dose given to the vivax malaria patients) might result in a fractional decline of up to approximately –20 % (approximately –2.5 g/dL). This evidence concerns the gene GSTM1 and Plasmodium vivax malaria.