In order to guide the assignment of HHCs to full-length TB treatment (Active TB) or preventive TB treatment (Mtb infected), we compared Active TB vs. Household contacts with Mtb infection (merged Mtb infected + recent QFT converters) and identified a 4-protein signature (bFGF, IFNγ, IL9, and IP10) with a specificity of 92.6%. The gene discussed is IL9; the disease is tuberculosis.