Figure 7

Seroprevalence and specificity of anti-MSP1-block 2 IgG in Dielmo. A) Seroprevalence to each family and family distribution within the parasite population. Seroprevalence was determined using sera collected during a cross-sectional survey conducted before the 1998 rainy season (on 2-3 August 1998) when 243 villagers (i.e. 95% of the village population) donated a fingerprick blood sample. The presence of anti-MSP1 block2 specific IgG was assessed by ELISA on 16 pools of biotinylated peptides (sequence and composition of the pools described in Table 5). Plasma reacting with one or more pool was considered seropositive, and grouped by family irrespective of the number of peptides sequences recognised within each of the three family types (i.e. MR alleles were disregarded as such, seropositivity being allocated either to Mad20 or to RO33). The relative distribution of family genotypes was established by nested PCR on 306 samples collected longitudinally during the 1990-9 time period as shown in Table 1. Colour codes K1: dark blue; Mad20: orange, RO33: light blue. B) Frequency of plasma with antibodies reacting with one, two and three allelic families. The number of families recognised is shown irrespective of the actual type recognised (i.e. individuals reacting with only K1-types, only Mad20-types or only RO33-types are placed together in the group reacting with one family). C) Frequency of reaction with each peptide pool.