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 reactive for ELISA, except in one
case. Sera tested by ELISA when diluted 1:200 allowed a clearer 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, sensitivity was 94% 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.
