GSTM1 and anemia: The proportion of children with anaemia (Hb < 11 g/dl) at the end of the high transmission season pre-IRS survey was 77.7%, and ranged between 67.8–72.5% during post-IRS surveys following application with a pyrethroid, and between 48.3–57.0% during post-IRS surveys following application with an organophosphate (Table 1).