A number of protein and glycoprotein antigens secreted by Mycobacterium tuberculosis (Mtb) have been identified as “early” Mtb antigens on the basis early antibodies present in subjects infected with Mtb prior to the development of detectable clinical disease. Epitope-bearing peptide fragments of these early Mtb antigens, in particular of an 88 kDa secreted protein, GlcB (SEQ ID NO:106) and of Mtb antigen MPT51 (SEQ ID NO:107) have been identified. These peptides, variants thereof, peptide multimers thereof that include two or more repeats of one or more of the peptides, and fusion polypeptides that include early Mtb antigenic proteins, peptides or both, are useful in immunoassay methods for early, rapid detection of TB in a subject. Preferred immunoassays detect the antibodies in the subject's urine. Also provided are antigenic compositions, kits and methods to useful for detecting an early Mtb antibodies. The antigenic proteins and peptides are also used in vaccine compositions.