Abstract

CHAMORRO, Luz et al. Agreement between an in-house indirect immunofluorescence assay and a commercial indirect hemagglutination test for detection of anti-Trypanosoma cruzi antibodies. Mem. Inst. Investig. Cienc. Salud [online]. 2023, vol.21, n.1, e21122311.  Epub Aug 31, 2023. ISSN 1812-9528.  https://doi.org/10.18004/mem.iics/1812-9528/2023.e21122311.

The serological diagnosis of Chagas disease, caused by Trypanosoma cruzi, lacks a "gold standard", being indirect immunofluorescence (IFI) considered the reference test for the detection of antibodies. Currently in Paraguay, the diagnosis is based on combining two serological tests. The objective of the study was to evaluate the agreement between an IFI in-house assay and a commercial indirect haemagglutination test (HAI) for the detection of IgG anti-T. cruzi. A total of 54 samples were evaluated, all from patients who attended the Instituto de Investigaciones en Ciencias de la Salud (IICS) with a medical request for Chagas serology. The specimens were first analyzed by IFI (29 positive and 25 negative) and stored in a serum bank, later they were thawed for analysis by HAI. Agreement between IFI and HAI was determined using the Kappa index. The agreement observed between both methods was very good (Kappa Index=0.96; p<0.0001). No significant differences were observed in the frequencies of samples that presented anti-T. cruzi IgG at low (p=0.759), intermediate (p=1,000) and high (p=0.592) levels. The antibodies measured by both methods showed a good correlation (Spearman's Rho= 0.715; p<0.01). The sensitivity and specificity of HAI versus IFI was 96.6% and 100%, respectively. The findings suggest that the combination of both tests, or HAI with other serological tests, would be a good diagnostic choice in Chagas disease at local level.

Keywords : Chagas disease; Trypanosoma cruzi; serological diagnosis; serological tests.

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