DIAGNOSIS OF AMEBIC DYSENTERY BY DETECTION OF ENTAMOEBA-HISTOLYTICA FECAL ANTIGEN BY AN INVASIVE STRAIN-SPECIFIC, MONOCLONAL ANTIBODY-BASEDENZYME-LINKED-IMMUNOSORBENT-ASSAY

An invasive strain-specific monoclonal antibody against Entamoeba hist olytica has been used in a capture enzyme-linked immunosorbent assay ( ELISA) for the detection of invasive E. histolytica fecal antigen in c linical specimens and for the diagnosis of amebic dysentery in patient s from Bangladesh. The fecal antigen capture ELISA (FAC-ELISA) did not cross-react with other parasite species in the clinical specimens or with noninvasive E. histolytica present in those specimens and in expe rimentally seeded stools. The limit of detection of the assay for inva sive E. histolytica crude antigen diluted in phosphate-buffered saline or in stools was 0.58 and 3.9 mug/ml, respectively, which is the equi valent of approximately 72 and 487 E. histolytica trophozoites per wel l, respectively. The sensitivity, specificity, and efficiency of the F AC-ELISA were 87, 100, and 98%, respectively, for the detection of inv asive E. histolytica antigens and 100, 100, and 100%, respectively, fo r the diagnosis of amebic dysentery. The FAC-ELISA is a potential alte rnative for the field diagnosis of amebic dysentery and for epidemiolo gical studies to define the distribution of invasive E. histolytica.