The ratio of IFN-γ/IL-10, CXCL10/IL-10, IFN-γ/IL-17, CXCL10/IL-17 and IL-17/IL-10 in response to ESAT-6 was significantly higher in both S2 spouses and TB patients compared with the S1 contact group (Figure 4A). This evidence concerns the gene IL17A and tuberculosis.