[Comparison between immunological and molecular techniques for the diagnosis of Chagas disease]

Chagas disease is caused by the parasite Trypanosoma cruzi. The disease involves an acute and chronic phases. The diagnosis has limitations, both in parasitological and immunological techniques. Molecular assays are an alternative, but these must be evaluated to determine its diagnostic usefulness. The aim of this study was to compare the effectiveness of immunological techniques with molecular assays in the diagnosis of Chagas disease in its different phases.

The immunological techniques used were ELISA, HAI and IFI and the molecular techniques used were PCR for amplification of kinetoplast minicircles, and satellite DNA of T. cruzi. Thirty-nine blood samples from patients in the acute phase of Chagas disease, and 42 samples from patients in the chronic phase were evaluated. In addition, 20 samples from healthy individuals and 10 patients with other diseases were also studied.

With immunological techniques were positive, 69.2% of samples from patients in the acute phase, while in the chronic phase were positive 95.2%. Using molecular techniques 79.5% of samples from patients in the acute phase were positive, while 23.8% of the samples from patients in the chronic phase were positive. None of the samples from healthy individuals was positive for any technique, while two samples from patients with other diseases were positive by the immunological assays.

The diagnostic efficacy of molecular techniques is high in the acute phase of Chagas disease, while in the chronic phase the immunological techniques are more effective.