Polypeptides are disclosed that are useful for diagnosing American trypanosomiasis, or Chagas disease, a disease caused by the infectious agent Trypanosoma cruzi. The polypeptides have a sequence that corresponds to the amino acid sequence of at least one of the C-terminal and N-terminal nonrepetitive regions of TCR27 protein. The polypeptide additionally may comprise an amino acid sequence of one or more repeats from the central region of TCR27 protein. In a preferred embodiment, the polypeptide corresponds to the N-terminal nonrepetitive region of TCR27 protein and at least one repeat from the central region of TCR27 protein, and does not correspond to the C-terminal nonrepetitive region. The polypeptides may further comprise a linker sequence at either the N-terminus or the C-terminus to facilitate attachment or conjugation to a carrier molecule in a liquid or solid support system for use in a sensitive assay for detecting T. cruzi infection.
