Preliminary evaluation of the commercial kit Chagas (Trypanosoma cruzi) IgG-ELISA® in Colombian individuals

Abstract

Introduction: The diagnosis of Chagas’ disease is essential to provide early treatment and improve patients’ prognosis. The discriminatory efficiency of the serological tests varies according to the disease prevalence and the test-antigen used.

Objective: To evaluate the discriminatory efficiency of the commercial kit Chagas (Trypanosoma cruzi) IgG-ELISA® (Nova Tec Immunodiagnostica GmbBH) in a group of Colombian individuals, using indirect immunofluorescence antibody testing (IFAT) and enzyme immunoassay (ELISA) tests as references.

Materials and methods: Seventy-eight samples from chronic chagasic patients (36 asymptomatic and 42 symptomatic) and 21 healthy controls were included. Seventeen samples from non-infected people with Chagas’ disease epidemiological risk, seven with leishmaniasis and nine with non-chagasic cardiomyopathy were also analyzed. Real time PCR was performed on four individuals whose results differed among tests.

Results: Significant differences at 450 nm optical absorbance were found (p<0.0001) when the median absorbance values of healthy controls (0.143), asymptomatic (2.401) and symptomatic (2.776) chagasic patients were compared, as well as when asymptomatic and symptomatic patients (p=0.0408) and seronegative people with epidemiological risk (0.232), cardiomyopathy (0.367) or leishmaniasis (0.337) were compared with chagasic patients (p<0.0001). Finally, there were differences among healthy controls and non-infected people with epidemiological risk (p=0.0264), patients with non-chagasic cardiomyopathy (p=0.0015) and patients with leishmaniasis (p=0.002). Real-time PCR was positive in three out of four analyzed cases.

Conclusions: The commercial ELISA test allowed us to discriminate the chagasic patients from the controls. A phase II study of diagnostic tests for determining field reliability of this test is required.