Antibody and P. falciparum infection profiles of individual children. The plots show the levels of IgG antibodies (y axis) to a panel of merozoite antigens at each of the six cross-sectional surveys (x axis) conducted between 1998 and 2003. The black solid arrows indicate the time during follow up when an individual child was parasitemic by microscopy. Asterisks indicate the time during follow up when a child had an episode of clinical malaria. The open triangles along the x axis indicate either the cross-sectional surveys when a child was aparasitemic or the weekly follow up visits when a child was symptomatic but found to be aparasitemic by microscopy. Red and blue arrows along the x-axis indicate the cross-sectional surveys at which a child was infected with P. falciparum clones of the IC-1 or FC msp2 types, respectively. Panel A-B, C–E and F–I show the profiles of children belonging to the malaria-free, single-episode and multiple-episodes groups, respectively. Ages are reported as at baseline, that is, in September 1998. IgG, immunoglobulin G.