There was a negative association between log10 malaria parasite count (parasites per 200 white blood cells) and Hb, but this was reduced in the adjusted model (crude regression coefficient −0.27, 95% CI −0.53 to −0.01, P = 0.039; adjusted regression coefficient −0.17, 95% CI −0.45 to 0.11, P = 0.206). This evidence concerns the gene GSTM1 and malaria.