Parasite responses to oxidative stress. Following the digestion of haemoglobin in the parasite vacuole, there is accumulation of FP, a toxic product that becomes polymerized into haemozoin. Some FP (free FP) may escape polymerization needing detoxification by the antioxidant machinery of the parasite. If not removed, the free FP reacts with phospholipids of the vacuolar membrane, increasing its permeability and leading to parasite killing. The parasite expresses two SODs (PfSOD-1 and SOD-2) and PfGST as part of its antioxidant machinery. Hg, haemoglobin.This figure appears in colour in the online version of JAC and in black and white in the printed version of JAC.