Standardization of serological tests for detecting anti-Trypanosoma cruzi antibodies in dogs

Abstract

This paper reports on the standardization of four serological reactions currently used in human serodiagnosis for the detection of anti-Trypanosoma cruzi antibodies in naturally and experimentally infected dogs. Indirect immunofluorescence test (IFAT) and hemagglutination test (IHAT) were standardized, and complement fixation test (CFT) and direct agglutination test (DAT) were used for diagnostic confirmation. Four hundred and eighty one mongrel dogs that were studied by xenodiagnosis were used: (1) parasitemic dogs of two localities of endemic area (EA) of Santiago del Estero province in Argentina (n = 134); (2) non-parasitemic dogs of the same area (n = 285); (3) dogs experimentally infected with T. cruzi in the patent period (n = 6); (4) non-infected dogs (n = 56) which were born in the city of Buenos Aires (BA), one non-EA for Chagas' disease. For IFAT, parasitemic dogs EA showed 95% of reactive sera. Non parasitemic dogs EA showed 77% of non reactive sera. None sera from BA were reactive for dilutions higher than four. For IHAT, 84% of sera of parasitemic dogs EA showed serological reactivity and among non parasitemic dogs BA, 61% were non reactive, while the remainder showed at most titres of 1/16. The cut-off titres for IFAT and IHAT were 1/16 and 1/32 respectively, and for CFT and DAT 1/1 and 1/128 respectively. Sensitivity for IFAT, IHAT, CF and DAT were 95%, 84%, 97% and 95% respectively.

Immunodiagnosis of Trypanosoma cruzi (Chagas' Disease) Infection in Naturally Infected Dogs

“…The present sensitivity estimate for IFAT agreed with a previous one (Lauricella et al 1993), in spite of using different commerically available conjugates. For IHAT, however, differences between a previous (84%) and the present sensitivity estimate (68%), separated by almost ten years, are not uncommon when different batches of commercially available kits are used.…”

“…Our study shows that ELISA was as sensitive as IFAT, which in previous studies was shown as the most sensitive technique among those assayed (Lauricella et al 1993). However, both ELISA and IFAT revealed sera reactive for T. cruzi that the other technique failed to detect.…”

“…For IHAT, a commercially available kit was used (Polychaco S.A.I.C, Buenos Aires, Argentina), and sera titrated in double dilutions to 1:128. Minimal IFAT and IHAT diagnostic titers of seropositivity for T. cruzi were 1:16 for both assays (Lauricella et al 1993).…”

“…In a previous study (Lauricella et al 1993), sera from 482 mongrel dogs were used to estimate sensitivity, specificity and the minimal diagnostic This study was supported by grants from the Rockefeller Foundation, New York, to Rockefeller University, New York, for a collaborative research project on modeling transmission dynamics and control of Chagas disease in Argentina (Roberto Chuit, Joel E Cohen and Ricardo Gürtler, principal investigators), and from the University of Buenos Aires. + Corresponding author.…”

Combined Use of Enzyme-Linked Immunosorbent Assay and Flow Cytometry To Detect Antibodies toTrypanosoma cruziin Domestic Canines in Texas

“…Estimates of seroprevalence in stray-canine populations in the lower Rio Grande Valley of Texas range up to 8.8% (9,12 A number of approaches have been used in the diagnosis of Chagas' disease, including xenodiagnosis, serological assays, and molecular detection methods. The use of serological assays, including radioimmunoprecipitation assay, direct and indirect hemagglutination, indirect immunofluorescent-antibody (IFA) testing, enzyme-linked immunosorbent assay (ELISA), and various combinations of these tests, has been described for the diagnosis of T. cruzi infection in canines (8,10,20,21,29,30,34,52,52). These serological tests have high sensitivity; however, their specificity may be low because of antigenic cross-reactivity with other parasitic species, such as Leishmania spp.…”