Pitting and surface area loss. (A) Quinine- vs AS-induced parasite clearance and pitting rates. Mean and SEM for (solid circles) parasitemia and concentration of (open circles) once-infected erythrocytes (both normalized against parasitemia at day 0) in patients with severe malaria treated either with quinine (n = 11) or AS (n = 16). (B) Concentration of circulating once-infected erythrocytes (billions of cells per liter) in patients with severe malaria treated with AS for whom posttreatment evolution of anemia could be categorized as (solid red circles) PADH (9 patients) and (solid black squares) non-PADH (12 patients). (C) Population frequency of erythrocytes—uninfected erythrocytes (uEs, yellow line; C2-C3), infected erythrocytes (iEs, blue line; C2), or once-infected erythrocytes (o-iEs, orange line; C3)—according to the projected surface areas (μm2) estimated on the bright field picture after identifying erythrocyte subtype by using a combination of immunofluorescent (IF) and Hoechst staining for parasite DNA. Uninfected erythrocytes were IF- and DNA-negative, infected erythrocytes were both IF- and DNA-positive, and once-infected erythrocytes were IF-positive and DNA-negative. Typical aspects are shown in panel C1. Samples were collected from the same patient at (C2) day 0 or (C3) day 4. At least 5000 infected or once-infected erythrocytes and 100 000 never-infected erythrocytes were analyzed. (D) (open circles) Individual values and (open bars) mean projected surface of uninfected and infected erythrocytes in samples from 4 patients on day 0 and of uninfected and once-infected erythrocytes from 4 patients on day 3 ± 1. The lines connect 2 subpopulations analyzed simultaneously in the same sample. The percentages indicate the mean decrease in projected surface area between uninfected and infected erythrocytes at day 0 or between uninfected and once-infected erythrocytes at day 3 ± 1.
