GSTM1 and infection: Children aged 5-11 years overall had significantly higher Hb levels if co-infected with hookworm (mean: 122.3 g/l, 95% CI: 119.0, 125.5 g/l) compared to individuals with P. falciparum mono-infection (mean: 115.4 g/l, 95% CI: 113.2, 117.5 g/l).