University of Tabriz Journal of Zoonotic Diseases 2476-535X 9 4 2025 09 01 Evaluation of the performance of two Chagas disease antibody tests in patients from the Chaco region (Argentina) 1037 1042 20117 10.22034/jzd.2025.20117 EN Romina Chiaraviglio Center for Research on National Endemic Diseases, Faculty of Biochemistry and Biological Sciences, National University of the Littoral, Santa Fe Province, Argentina Carolina Aro Chair of Parasitology, Faculty of Biochemistry and Biological Sciences, National University of the Littoral. Santa Fe Province, Argentina Diego Mendicino National Scientific and Technical Research Council, Santa Fe Province, Argentina Journal Article 2025 03 16 Chagas disease (CD) is caused by the protozoan <em>Trypanosoma cruzi</em> and is a significant zoonotic disease affecting millions worldwide. The disease progresses from an often asymptomatic acute phase to a chronic phase, which can lead to severe cardiac or digestive issues in about 30% of untreated individuals after 20 to 30 years. Early diagnosis and treatment are crucial to managing the disease and preventing further transmission. Diagnosis typically involves serological tests to detect anti-<em>T. cruzi</em> antibodies, with the Indirect Hemagglutination Assay (IHA) and ELISA being the most common methods. Given the antigenic diversity of the parasite, the Pan American Health Organization (PAHO) recommends the use of two different tests for a reliable diagnosis. The objective of the present study was to evaluate the performance of two commercial diagnostic assays for chronic CD in the Chaco Region. Blood samples were collected from 388 patients from the Chaco Region between November 2019 and November 2023, and the results showed a high degree of agreement between the IHA and Lysate ELISA commercial tests. However, Lysate ELISA was found to produce more false negatives compared to the PAHO diagnostic algorithm, which could leave patients untreated and contribute to ongoing transmission. The study demonstrated very good performance of the commercial tests evaluated. However, the presence of some false results underscores the importance of continuing to use the PAHO algorithm based on two serological tests for reliable diagnosis in the region. https://jzd.tabrizu.ac.ir/article_20117_01133717e114fb2bff952234928dbf55.pdf