Evaluation of serological tests to identify Trypanosoma cruzi infection in humans and determine cross-reactivity with Trypanosoma rangeli and Leishmania spp

Abstract

Five commercially available enzyme-linked immunosorbent assays (ELISAs), one in-house ELISA, and two hemagglutination assays were evaluated to determine their diagnostic accuracy for Chagas' disease in two studies. In study 1, ELISA kits showed 100% sensitivity, but specificities ranged from 82.84% to 100% when leishmaniasis cases were included and from 95.57% to 100% when leishmaniasis cases were excluded. Kits using recombinant antigens or synthetic peptides are more specific than those using crude extracts from Trypanosoma cruzi epimastigote forms. Kits evaluated in Panama, in study 2, showed 75% to 100% sensitivity and 97.12% to 100% specificity. These data were obtained by using a Western blot assay with T. cruzi trypomastigote excreted-secreted antigens as a reference test to confirm T. cruzi infection.

FIG. 1.

Distribution of individual results of five commercially available ELISAs (Chagas III, ELISAcruzi, Chagatek, Chagatest Rec v3.0, and Pathozyme) and one in-house ELISA (ELISA-IMT) for diagnosis of Chagas' disease. The first five groups of data in each graph are results, from study 1, for 53 Brazilian individuals with T. cruzi infections (Ch), 45 healthy individuals (H), 21 patients infected with Leishmania spp. (L), 23 individuals infected with Trypanosoma rangeli (Tr), and 45 patients with other infections (OI). The last group of data in each graph (Study 2) corresponds to 16 TESA-blot-positive Panamanian cases. The horizontal line within each data group is the arithmetic mean. Each data point was calculated as the ratio of the OD to the cutoff. The horizontal line at 1.0 unit represents the cutoff.