Evaluation of Chagas TESA VirClia assay for chronic Trypanosoma cruzi infection diagnosis and post-treatment follow-up.

Diagnosis of chronic Trypanosoma cruzi infection relies on the concordant results of two serological tests based on different antigens and/or principles. Currently, the only accepted cure criterion is the switch from positive to negative serology, but anti-T. cruzi IgG may persist for years, even after treatment. Recently, a novel chemiluminescence immunoassay based on native T. cruzi excreted-secreted antigens (TESA)-Chagas TESA VirClia-was developed. This study assessed the performance of this assay for the detection of anti-T. cruzi antibodies for the diagnosis and post-treatment follow-up of chronic T. cruzi infection. A retrospective diagnostic accuracy study was conducted using 227 serum samples, including samples from individuals tested for chronic T. cruzi infection and from individuals with other parasitic or viral infections. T. cruzi infection status was established using two reference serological assays based on recombinant and native antigens. All samples were analyzed by TESA-based assay and compared with the reference tests. Concordance between the TESA-based assay and the reference tests was 93.8%, with a sensitivity and specificity of 92% and 100%, respectively. Limited cross-reactivity was observed in samples positive for Leishmania spp. antibodies, while no cross-reactivity was observed in viral infections. A decrease in antibody index over time was observed more frequently in treated patients when tested by the TESA-based assay. These findings support the use of the Chagas TESA VirClia assay as a reliable confirmatory tool within the diagnostic algorithm for chronic T. cruzi infection. Moreover, this assay was the only test showing a consistent post-treatment decline in antibody index over time.IMPORTANCEThe diagnosis and monitoring of chronic Trypanosoma cruzi infection remain challenging because no single serological test achieves 100% sensitivity and specificity, and the antibodies may persist for many years even after treatment. This study highlights the value of a novel serological assay based on native antigens excreted by the parasite, which more effectively reflects changes in antibody levels over time. Its high diagnostic accuracy and greater ability to detect declining antibody values in treated patients support its use as a reliable diagnostic tool as well as a promising method for serological follow-up.