Laboratory Diagnosis for Giardia Lamblia Infection: A Comparison of Microscopy, Coprodiagnosis and Serology

Abstract

MA BEHR, E KOKOSKIN, TW GYORKOS, L CÉDILOTTE, GM FAUBERT, JD MACLEAN. Laboratory diagnosis for MAIN RESULTS:For 152 previously collected stools, copro-antigen detection had a sensitivity of 73 of 74 (98.6%) and a specificity of 78 of 78 (100%). In clinical samples of 62 patients, eight of the 62 patients (13%) were diagnosed with G lamblia infection on microscopy. Copro-antigen diagnosis was accurate in symptomatic patients, with sensitivity of seven of eight (87.5%) and specificity of 52 of 54 (96.8%). Serology was less accurate. IgG response to G lamblia had sensitivity of four of seven and specificity of 24 of 50 (48%), and IgM response had sensitivity of three of six and specificity 27 of 48 (56%). Western blot had a sensitivity of five of seven and a specificity of 38 of 49 (78%). CONCLUSIONS: Copro-antigen diagnosis of G lamblia is highly accurate in patients with chronic gastrointestinal complaints, while serology is less accurate and appears to be less useful diagnostically.

Diagnosis of Human Giardiasis

“…Faubert, 2000). According to Faubert (2000), all studies using the ELISA-GSA 65 antigen report greater sensitivity with ELISA than microscopy on a single specimen, and the sensitivity varies between 95 and 100%, with 100% specifi city reported when used with stools from patients infected with various intestinal parasites (Behr et al, 1997;Rosoff and Stibbs, 1986). According to Faubert (2000), all studies using the ELISA-GSA 65 antigen report greater sensitivity with ELISA than microscopy on a single specimen, and the sensitivity varies between 95 and 100%, with 100% specifi city reported when used with stools from patients infected with various intestinal parasites (Behr et al, 1997;Rosoff and Stibbs, 1986).…”

Immune Response to Giardia duodenalis

“…In Table 1, the results obtained by different laboratories with a variety of serological assays for the detection of Giardia antibodies in serum of proven cases are summarized. Proven cases of giardiasis were defined as follows: "patients passing cysts in their feces and/or presenting with one or more of the clinical symptoms of giardiasis" (15).…”

“…In fact, all studies with the ELISA-GSA 65 have reported a greater sensitivity of the immunodiagnosis assay over the microscopic examination of a single specimen ( Table 1). The sensitivity of the assay varies between 95 and 100%, and 100% specificity has been reported when it was used with stools from patients infected with other intestinal parasites (15,162). It has been reported that the ELISA-GSA 65 can detect Giardia infection in at least 30% more cases than the microscopic examination (163).…”

“…These results clearly demonstrate the superior sensitivity of the rapid enzyme assay in detecting cases of giardiasis in epidemiological studies when a single specimen is analyzed. In contrast to all the serological assays used for the detection of antibodies against Giardia proteins, the ELISA-GSA65 for the detection of antigens in feces has demonstrated a remarkable sensitivity and specificity of 98 and 100%, respectively (15).…”

A Comparison of Microscopy and Enzyme Linked Immunosorbent Assay for Diagnosis of Giardia lamblia in Human Faecal Specimens

“…It is distributed worldwide with an estimated global prevalence of 280 million cases per annum [2]. Its mode of transmission is faeco-oral due to consumption of contaminated food or water or by person to person contact in homosexuals [3]. G. lamblia infection generally causes a varied spectrum of disease ranging from the asymptomatic carrier state to acute fulminating diarrhoea or persistent diarrhoea with malabsorption in children and adults [4].…”