Immunodiagnosis of Trypanosoma cruzi (Chagas' disease) infection in naturally infected dogs

RESUMEN

This study reports on the standardization of an enzyme-linked immunosorbent assay (ELISA) for detecting specific antibodies anti-Trypanosoma cruzi in naturally infected dogs. Sera from 182 mongrel dogs of all ages residing in four rural villages in Santiago del Estero, Argentina, were collected in November 1994 and preserved in buffered neutral glycerin. All sera were tested by indirect hemagglutination test (IHAT), indirect immunofluorescence test (IFAT), and ELISA using the flagellar fraction of T. cruzi as antigen. Dog sera from an area without vectorial transmission were used to calculate ELISA specificity and cut-off-value. Eighty-six percent of sera had concordant results for all tests. All sera reactive for IHAT and IFAT were also rective for ELISA, except in one case. Sera tested by ELISA when diluted 1:200 allowed a clearer division between non-reative and reactive sera than when 1:100 with greater agreement among serologic techniques. The specificity of ELISA was 96,2 per cent. Among 34 adult dogs with a positive xenodiagnosis, sensitivity was 94 per cent both for ELISA and IFAT. ELISA is the first choice for screening purposes and one of the pair of techniques recommended for diagnostic studies in dog populations.