IMMUNODIAGNOSIS OF TRYPANOSOMA-CRUZI (CHAGAS-DISEASE) INFECTION IN NATURALLY INFECTED-DOGS

This study reports on the standardization of an enzyme-linked immunoso rbent assay (ELISA) for detecting specific antibodies anti-Trypanosoma cruzi in naturally infected dogs. Sera from 182 mongrel dogs of all a ges residing in four rural villages in Santiago del Estero, Argentina, were collected in November 1994 and preserved in buffered neutral gly cerin. 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 vector ial 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 reactive for ELISA, ex cept in one case. Sera tested by ELISA when diluted 1:200 allowed a cl earer division between non-reactive and reactive sera than when 1:100 with greater agreement among serologic techniques. The specificity of ELISA was 96.2%. Among 34 adult dogs with a positive xenodiagnosis, se nsitivity was 94% both for ELISA and IFAT. ELISA is the first choice f or screening purposes and one of the pair of techniques recommended fo r diagnostic studies in dog populations.