ELISA titers against late-stage parasite extract. Antibody levels in 7 non-immune Danish travellers with a single episode of clinical malaria (A), 8 Ghanaian children (0-5 years) (B), 6 Ghanaian children (6-10 years) (C), 12 Liberian adults clinically immune to malaria (D), and 35 non-immune Danish controls (E). Each point represents one plasma sample. OD492, optical density at 492 nm. The horizontal lines mark the mean value. Open circles mark the plasma samples for representative profiling of antibody reactivity against parasite proteins using Western Blot analysis have been shown (Fig. 2).