Fig. 2

Proportions of positive parasitaemia in different haemoglobin genotypes (n = 688). Bars show percentages of positives in the respective genotype group, and lines represent individual 95% confidence interval. The basically reversed proportions in the aa/aa with AS and -a/aa with AS groups illustrate the effect of the sickle cell trait that is also present in asymptomatic parasite carriers. aa/aa with AA = wild type, -a/aa with AA = single deletion of 3.7 kb or 4.2 kb, aa/aa with AC = haemoglobin C (heterozygous), -a/aa with AC = single deletion of 3.7 kb with haemoglobin C (heterozygous), aa/aa with AS = haemoglobin S (heterozygous), -a/aa with AS = single deletion of 3.7 kb with haemoglobin S (heterozygous); rarer traits = other genotype (details in Additional file 1: Tables S2, S3)