Detection of a giardia lamblia coproantigen by using a commercially available immunoenzymatic assay, in belo horizonte, brazil

• Published in: Revista do Instituto de Medicina Tropical de São Paulo 1999-05, Vol.41 (3), p.151-154
• Main Authors: Rocha, MO, Mello, RT, Guimaraes, TM, Toledo, Vd, Moreira, Md, Costa, CA
• Format: Article
• Language: English
• Subjects: TROPICAL MEDICINE
• ISSN: 0036-4665; 1678-9946; 1678-9946; 0036-4665
• DOI: 10.1590/s0036-46651999000300003

It is known that fecal examination to detect Giardia lamblia cysts or trophozoites produces a high percentage of false-negative results. A commercially available immunoenzymatic assay (ProSpecT Giardia Microplate Assay, Alexon, Inc., BIOBRAS) to detect G. lamblia specific coproantigen was evaluated for the first time in Brazil. A total of 90 specimens were tested. Each specimen was first tested as unpreserved stool, and then it was preserved in 10% Formalin to be tested 2 months later. The assay was able to identify all the 30 positive patients (sensitivity = 100.0%) by visual or spectrophotometric examination in the unpreserved specimens and was negative in 57 of the 60 patients without G. lamblia (specificity = 95.0%). The assay identified 27 of the 30 positive patients (sensitivity = 90.0%) and was negative in 59 of the 60 negatives (specificity = 98.3%) in the preserved stools according to both readings. A marked difference was observed in the optical densities in both groups, preserved and unpreserved stools, when the G. lamblia-positive specimens were compared to the negative or positive for other intestinal parasites than G. lamblia. The assay seems a good alternative for giardiasis diagnosis, especially when the fecal examination was repeatedly negative and the patient presents giardiasislike symptoms.