Platelet binding in clinical malaria blood samples. (A) Photos of platelet-bound iRBCs from patient Giemsa smears (black arrowhead = platelet). Images were taken at 1000× magnification using a Samsung Note-3 camera attached to an Olympus CX31 microscope. Scale bar, 5 µm. (B) Representative flow cytometry gating strategy to measure platelet binding in a P falciparum patient and healthy control. (C) Frequency of platelet-bound uRBCs by flow cytometry in patients with malaria compared with control patients in samples from (Ci) Papua (control patients, n = 17; Pf, n = 23; Pv, n = 26; Pm, n = 9; mixed, n = 7) and (Cii) Sabah (control patients, n = 28; Pf, n = 14; Pv, n = 85; Pk, n = 106; Kruskal-Wallis, *significantly different to all other groups). (D) Frequency of platelet-bound iRBCs and uRBCs by flow cytometry in samples from (Di) Papua (n as per Ci) and (Dii) Sabah (n as per Cii; Wilcoxon test). (E) Inverse correlation of platelet-bound iRBCs with parasitemia in samples from (Ei) Papua and (Eii) Sabah (Spearman). Scatterplots indicate median ± interquartile range for each group. Parasitemia values are log transformed. Data presented in supplemental Table 1. Pf, P falciparum; Pv, P vivax; Pm, P malariae; Pk, P knowlesi.