The Hb, Hct, RBC, WBC and platelet values were significantly lower in individuals with co-infections as compared to single infections with either STH or P. falciparum. The similarities in mean red cell indices in those with a single STH infection and lower values in those co-infected with a helminth only or P. falciparum single infection accentuate the influence of any co-infection and P. falciparum infection on haematological parameters. This evidence concerns the gene GSTM1 and infection.