Immune reactivity in malaria exposed sera. A, Immunoglobulin G (IgG) responses against recombinant PfRH2D1, PfRH5, and MSP 1–19 were assessed in low (Thies) and high (Velingara) endemicity plasma by enzyme-linked immunosorbent assay. Percentage positive responses are shown based on 3σ cutoff to Boston controls. B, Stratification of PfRH2D1 optical density (OD) by median age in low-endemicity samples (Thies). C, Stratification of PfRH2D1 OD by median age in high-endemicity samples (Velingara). D, Stratification of PfRH5 OD by median age in low-endemicity samples (Thies). E, Stratification of PfRH5 OD by median age in high-endemicity samples (Velingara).