Validation of a particle gel immunoassay for Trypanosoma cruzi antibody detection using plasma samples collected with capillary tubes

Abstract

Introduction: The Chagas disease particle gel immunoassay (PaGIA-Chagas) is a simple, fast and practical test used for the diagnosis of the chronic Chagas disease and is based on anti-Trypanosoma cruzi antibody detection in serum. This study aimed to validate the PaGIA-Chagas on plasma collected with capillary tubes. Methodology: Serum samples from 74 T. cruzi-infected and 26 non-infected individuals were tested by conventional indirect immunofluorescence and PaGIA-Chagas. Later, plasma specimens collected with capillary tubes from these same individuals were tested by PaGIA-Chagas. Results from serum samples tested by IFA and PAGIA-Chagas were considered as the reference standard to determine the accuracy parameters of the particle gel tested on plasma samples. The inter-test agreement of T. cruzi antibody detection by PaGIA-Chagas on serum and plasma was calculated using Kappa index. Results: The PaGIA-Chagas performed on plasma collected with capillary tubes had sensitivity and specificity of 99% and 100%, respectively. The crude agreement observed with the results of the PaGIA-Chagas on plasma and serum was 99% and the Kappa index was 0.975 (CI95%: 0.782 -1.000). Conclusion: PaGIA-Chagas for anti-T. cruzi detection on plasma collected with capillary tubes is accurate and might be indicated to reduce fieldwork time and materials in epidemiological screening of chronic Chagas disease.

Development of Chemiluminescent Lateral Flow Assay for the Detection of Nucleic Acids

“…The currently accepted methods for the detection of Trypanosoma such as microscopic examination and xenodiagnoses have poor sensitivity and are also labor-intensive and time-consuming [ 1 , 2 ]. Immunological methods such as enzyme-linked immunosorbent assay, immunochromatographic dipstick test, radioimmunosorbent assay, and immunofluorescence antibody test are rapid and sensitive but not specific [ 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. Molecular methods such as PCR and real-time nucleic acid sequence-based amplification are very specific but expensive and time consuming, although combination of PCR and chemiluminescence southern blot has been used to improve the sensitivity of the detection of Trypanosoma [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ].…”