Evaluación de la sensibilidad y especificidad de reactivos para la determinación de anticuerpos para Chagas en los Bancos de Sangre

Abstract

Chagas disease is a common endemic disease in Latin America caused by the protozoan Trypanosoma cruzi. Currently, there is no gold standard for its diagnosis. The aim of this study was to analyze which would be the most sensitive serological pair for screening and choose which would work best to raise reaction specificity of diagnosis in a second step. A total of 52 samples from our preservedsera collection and 138 freshly extracted samples were tested in parallel with different  reagents. Commercial reagents for Gelatin Particle Agglutination, Indirect Hemagglutination and ELISA were used. The relative individual sensitivity of the reagents oscillated between 75 and 100%, whereas that for serological pairs was between 91.67 and 100%. Specificity values for serological pairs ranged from 56.82 to 90.78%, reaching values of up to 98.45% when adding a third reaction. If the screening is done with a single reagent, we recommend being very careful in its selection, given the wide dispersion of results in terms of sensitivity. The serological pair increased the sensitivity in every case. The introduction of the third reaction increased the specificity values and the positive predictive value, but never reached 100%.