COMPARISON OF IMMUNOFLUORESCENCE ASSAY, S TOOL EXAMINATION AND DUODENAL BIOPSY FOR THE DIAGNOSIS OF GIARDIA-INTESTINALIS INFECTION

For the diagnosis of giardiasis, the immunofluorescence assay (IFA) us ing a mouse monoclonal antibody specific for wall antigens of Giardia intestinalis cysts was compared with classical stool examination metho ds and with pathological examination of duodenal biopsies. Stool sampl es from sixty-eight patients were tested by IFA, direct examination of stools and Thebaut's concentrating method. Eighty-four samples of duo denal fluid were tested by IFA and direct examination, coupled with pa thological examination of duodenal biopsies. Using Thebaut's method as a reference, sensitivity of direct examination was 89.4 p. cent, and that of IFA was 94.7 p. cent. Thebaut's method and IFA strongly correl ated, when IFA yielded higher parasitic densities. For an immunocompro mised patient with a regimen of multiple anti-infectious drugs, IFA di agnosed a Giardia infection that escaped usual stool examination metho ds. Pathological examination of duodenal biopsies found 3 positive cas es, none of which was associated with a positive IFA result from duode nal fluid samples.