DETECTION OF GIARDIA-LAMBLIA CYSTS IN STOOL SAMPLES BY IMMUNOFLUORESCENCE USING MONOCLONAL-ANTIBODY

The diagnostic potential of indirect immunofluorescence to detect Giar dia cysts in stool samples using a cyst-specific anti-Giardia lamblia monoclonal antibody was evaluated in comparison to conventional light microscopy. One hundred fifty specimens from clinically suspected Giar dia infections and 50 control samples from microscopically proved Giar dia infections were tested, Giardia cysts were found in 15 of 150 (10 %) samples tested by light microscopy, whereas immunofluorescence micr oscopy detected 35 of 150 (23 %) positive samples. Forty-six of the 50 reference samples previously shown to contain Giardia cysts were posi tive. Apparently, the four discrepant samples contained very low numbe rs of parasites, as none could be detected by conventional microscopy. The results show that Giardia lamblia cysts are detected significantl y more frequently using the antibody marker. The doubled number of pos itive stool specimens and detection of as little as four cysts per sam ple suggest that microscopical examination of samples can be improved by immunofluorescent staining of Giardia lamblia cysts.