This modest increase in ITN use was associated with a decrease in moderate to severe anaemia (Hb <8 g/dl) from 18.4% (95% CI:14.9%-21.8%) in 2005 to 15.4% (13.2%-17.7%) in 2008, while parasitaemia, measured as positive-slide microscopy, decreased from 18.9% (95% CI:14.7%-23.2%) to 16.9% (95% CI:13.8%-20.0%), a relative reduction of 16% and 11%, respectively. Here, GSTM1 is linked to anemia (phenotype).