Use of a Monoclonal Antibody in an Enzyme Immunoassay for the Detection of Entamoeba histolytica in Fecal Specimens

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  • Division of Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, Maryland and National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20205

An indirect enzyme-linked immunosorbent assay (ELISA) was developed for the detection of Entamoeba histolytica in human feces, using both a monoclonal antibody and rabbit antisera. It detected from less than 1 to 57 trophozoites of 6 E. histolytica strains. Stool specimens were positive by ELISA in 18 of 22 (82%) patients with E. histolytica and in 3 of 186 (2%) of patients without demonstrable E. histolytica in their stools. The latter included one from a child living near an asymptomatic cyst carrier and another from a traveler with giardiasis who had recently taken antibiotics. One hundred eight of 183 microscopy- and ELISA-negative specimens contained other parasites including Giardia (49 specimens), Endolimax nana (24), Entamoeba coli (21), Iodamoeba butschlii (2), and Entamoeba hartmanni (1). This ELISA for E. histolytica is a simple, sensitive and specific diagnostic tool.