Dados do Trabalho

Título

A High-Performance Lateral Flow Rapid Test to Diagnose Chronic Chagas Disease

Introdução

Chagas disease is caused by the protozoan Trypanosoma cruzi and can manifest clinically decades after infection as cardiomyopathy, megaesophagus, or megacolon. Of the projected 6-7 million infected individuals, a large majority are unaware of their positive status. Diagnosis of chronic Chagas disease is essentially serological, requiring reactivity in two methods, usually ELISA and indirect immunofluorescence (IFI), although protocols that are time consuming and burdensome. Incorporation of testing into the United Health System could identify persons infected before the interruption of vector transmission in the 1990s for clinical assessments, which would require a high-performance assay. 

Objetivo (s)

Assess the performance of a new lateral flow rapid test prototype employing DxCruziV3, an innovative deca-epitope protein for capturing anti-T. cruzi antibodies in the Piauí state. 

Material e Métodos

A panel of sera obtained during a 2018 cross-sectional survey in São João do Piauí was utilized. Samples had been diagnosed at the time of collection by ELISA (Chagatest recombinant ELISA v.3, Wiener Lab, Rosario, Argentina) and IFI (IFI Chagas Disease, Bio-Manguinhos) before storage at -20 °C. Here, 16 samples positive by both assays along with 24 negative samples were screened. The study was approved by the Ethics Committee of Fiocruz: CAAE: 52892216.8.0000.5248

Resultados e Conclusão

Of the 16 ELISA+IFI positive samples, 12 were positive and 4 were negative according to the DxCruziV3 rapid test. For the 24 negative samples, all were negative in the rapid test. This resulted in the following performance parameters: specificity = 100%; sensitivity = 75%; Positive Predictive Value = 100%; Negative Predictive Value = 85.7%; Agreement = 90%; Kappa index = 0.782. The sensitivity of 75% reflected the 4 samples reactive by ELISA+IFI but not in the DxCruziV3 rapid test. The DxCruziV3 rapid test demonstrated a good performance for the detection anti-T.cruzi antibodies in samples collected from a high-prevalence endemic area, even after storage for 6 years at -20°C. The reduction in sensitivity may be related to the incomplete suspension of immunoglobulin, half-life (~20 days), and protein degradation in the stored sera. Yet, DxCruziV3 could still capture sufficient quantities of antibodies in most positive samples for detection and did not show any non-specific reactivity. Rapid tests using DxCruziV3 have a potential application to screen people from endemic areas for chronic T. cruzi infections.

Palavras Chave

Chagas disease; rapid test