Both synthetic peptides Am1 and Am2 presented high reactivity against sera of A. marginale infected animals; however, when both were tested (ELISA) for reactivity to other diseases, the Am1 specifically reacted with IgG antibodies from anaplasmosis (p<0.05), while the Am2 presented cross-reactivity with bovine brucellosis (Figure 3). The gene discussed is ADM2; the disease is human granulocytic anaplasmosis.