The ID-Chagas test is a particle gel immunoassay (PaGIA). Red coloured particles are
sensitised with three different synthetic peptides representing antigen sequences of
Trypanosoma cruzi: Ag2, TcD and TcE. When these particles are mixed with serum
containing specific antibodies, they agglutinate. The reaction mixture is centrifuged through a
gel filtration matrix allowing free agglutinated particles to remain trapped on the top or
distributed within the gel. The result can be read visually. In order to investigate the ability of
the ID-PaGIA to discriminate negative and positive sera, 111 negative and 119 positive,
collected in four different Brazilian institutions, were tested by each of the participants. All
sera were previously classified as positive or negative according to results obtained with three
conventional tests (indirect immunofluorescence, indirect hemaglutination, and enzime linked
immunosorbent assay). Sensitivity rates of ID-PaGIA varied from 95.7% to 97.4% with mean
sensitivity of 96.8% and specificity rates varied from 93.8 to 98.8% with mean specificity of
94.6%. The overall Kappa test was 0.94. The assay presents as advantages the simplicity of
operation and the reaction time of 20 min. In this study, ID-PaGIA showed to be highly
sensitive and specific.
