The present invention relates to methods and compositions for preventing, treating and diagnosing infection by trypanosomes. The invention also relates to the use of excreted/secreted antigens (exoantigens, secretome) and specifically to the identification of a protein excreted/secreted by the trypanosomes, the inhibition of which makes it possible to provide effective protection, mainly by vaccination, against infection by trypanosomes or the development or spread thereof. The invention relates to use of the protein, the derivatives thereof, a nucleotide sequence derived from said protein, or an extract enriched with said protein, and to the use of antibodies directed against said trypanosomes for immunotherapy, diagnosis, and monitoring of infections by trypanosomes.
