Comparative evaluation of immunoassays to improve access to diagnosis for Chagas disease in Colombia

Abstract

Objective: Chagas disease affects over six million people, but less than 1% are diagnosed and treated. Complicated diagnostic processes are a major barrier. Colombia's previous diagnostic algorithm, using in-house tests, was difficult to scale up, creating significant access barriers for patients. A new algorithm using commercially manufactured immunoassays would potentially improve access, but these tests' performance in Colombian patients with Chagas disease is not well known.

Methods: We assessed seven commercially available assays. Samples (n=501), 93.8% originating from Colombia, were characterized as positive or negative based on standard procedure at the National Reference Laboratory. Performance characteristics were calculated for individual assays and hypothetical test pairings, then compared to the existing algorithm.

Results: Five of seven assays exhibited sensitivity >98% while six showed specificity >97%. A total antigen ELISA paired with a recombinant assay provided similar performance to the current diagnostic process. Six of six assays tested proved capable of detecting different Trypanosoma cruzi genetic lineages.

Conclusions: The study indicated that several commercial assays accurately detect T. cruzi infection in Colombian patients. A simplified testing process with two commercial assays could perform comparably to the previous process, reducing cost and accessibility barriers and facilitating national scale-up.

Keywords: Access to healthcare; Chagas disease; Diagnostic barriers; Enzyme-linked immunosorbent assays; Neglected tropical diseases (NTDs); Trypanosoma cruzi.