GSTM1 and anemia (phenotype): P. falciparum gametocytes were most commonly present in participants with mild anaemia (Table 2, Hb 8.0–10.9g/dL, 66.0%, P = 0.008), whereas P. vivax gametocytes were most common in participants with moderate-to-severe anaemia (Hb <8g/dL; Table 3, 90.0%).