Evaluación del rendimiento diagnóstico de técnicas ELISA para la Enfermedad de Chagas en Colombia

Abstract

Introduction: Chagas disease is caused by the protozoan Trypanosoma cruzi, endemic in America Latina. Diagnosis is complex, which currently poses a barrier to treatment access. The World Health Organization recommends chronic phase diagnosis with a combination of two serologic tests with different antigenic configurations. The current procedure in Colombia is initial screening with an ELISA with confirmation by an immunofluorescent assay (IFA). Objective: Evaluate the diagnostic performance of seven conventional and unconventional ELISA tests for detection of T.cruzi antibodies. Methodology: This was an observational study using 501 serum samples from Colombian patients which measured operational characteristics of ELISA tests individually and in binomial combinations against current procedures used by the Colombian National Institute of Health, to help configure a new serologic diagnostic algorithm. Results: Individual sensitivity ranged from 92.5 to 99.6%, and specificity ranged from 94.6 to 97.9%. Use of simultaneous binomial combinations produced higher sensitivity, while specificity was increased with sequential combinations, up to 99.9% in some cases. Discussion: Total antigen assays performed well for screening of the general Colombian population. Their antigenic configuration permits detection of the majority of positive patients. The majority of recombinant tests were adequate for detection of suspected cases, performing nearly as well as the IFA. Conclusion: Performance of most of test was appropriate, therefore, two-stage testing should consist of a total antigen assay in the first stage followed by a recombinant or synthetic peptide test. This would allow for replacement of the indirect immunofluorescence assay as a confirmatory test, eliminating an important barrier to diagnosis in Colombia.