Utilisation of T. evansi antigens in indirect-ELISA for diagnosis Chagas disease in humans

Chagas disease has a very low incidence in French Guyana, estimated at 5-10 cases a year. For this reason, tests are not locally available, and samples must be sent by courrier to Metropolitan France. Two cases of Chagas diseases with cardiac symptoms were suspected by a cardiologist in Hospital; serum samples were submitted to our laboratory. Antigenic similarities between salivarian and stercorarian trypanosomes have been very little investigated, so the potential use of #T. evansi# antigens for the diagnosis of #T. cruzi# infection was evaluated. Western blottings on "T. evansi# antigens showed reactions of the two send while 4 negative samples did not react at all. In Indirect-ELISA #T. evansi# the reponses of the two sera were very strong. 50 sera from the serum bank of Pasteur Institute were used as negative controls. The rate of optical density of suspected sera/negative control were 10 to 40. Infection of these two sera was later confirmed in homologous system by Pasteur Institute in Paris. Evaluation of the indirect-ELISA #T. evansi# for the diagnosis of Chagas disease in human was conduced in collaboration with F. Brenière, from ORSTOM Bolivia; 211 reference sera were tested in blind CIRAD-EMVT-Guyane . Cut off line of the indirect-ELISA #T. evansi# was later on determined on the basis of the results to several other tests specific of #T. cruzi# that were performed, among which PCR, Buffy coat, ELISA lgG and lgM, hemagglutination, immunofluorescence. Sensitivity and specificity of the new test was not significantly different from the other serological tests based on #T. cruzi# antigens, showing the potential use of the indirect-ELISA #T. evansi# the diagnosis of Chagas disease in humans. (Résumé d'auteur