The mechanisms of parasite clearance after antimalarial treatment of Plasmodium falciparum malaria

Studies were conducted to determine how malaria parasites are cleared from the blood after antimalarial treatment, Neither artesunate nor quinine decr eased parasitized red cell deformability or increased antibody binding, In acute falciparum malaria, ring-infected erythrocyte surface antigen (RESA) was observed in erythrocytes without malaria parasites (RESA-red blood cell [RBC]), indicating prior parasitization. In uncomplicated malaria, RESA-RB C numbers increased significantly (P = .002) within 24 h of starting artesu nate but rose much more slowly (7 days) after quinine treatment, In severe malaria, RESA-RBC increased significantly (P = .001) within hours of starti ng artesunate but not with quinine treatment (P = .43), RESA-RBCs were not produced after drug treatment of malaria parasite cultures in vitro. Rapid malaria parasite clearance after treatment with artemisinin derivatives res ults mainly from the extraction of drug-affected parasites from host erythr ocytes-presumably by the spleen. This explains why the fan in hematocrit af ter treatment of hyperparasitemia is often less than that predicted from lo ss of parasitized cells.