Chagas serology and its problems

Abstract

Summary. We performed a comparative study (263 sera) of four serological techniques for the diagnosis of Chagas' disease (IFT, CFT, ELISA, IEP). The concordance of the four techniques was 92.8 per cent, and we obtained good quantitative correlations between IFT, CFT and ELISA techniques. Looking at the positivity or negativity of three out of four techniques in order to sort out positivity and negativity of the sera, we obtained a relative sensitivity for the techniques from 96 per cent to 100 per cent, and a relative specificity from 95.1 per cent to 100 per cent. On the other hand, we evaluated the ELISA and IEP techniques. Both techniques appeared to be valuable for Chagas' diagnosis. 150 patients were submitted to xenodiagnosis and their sera were analysed for Chaga's disease. Four of them without any previous treatment appeared to have a peculiar status with positive xenodiagnosis and negative serology. The authors suggest the systematic practice of xenodiagnosis and serodiagnosis. Besides, the development of a test for detecting circulating antIgens of T. cruzi could be useful for the implementation of the classical serology on these patients.