Early, intermediate, and late acute stages in Chagas' disease:: A study combining anti-galactose IgG, specific serodiagnosis, and polymerase chain reaction analysis

The acute phase of Chagas' disease was classified as early, intermediate, and late based on the levels of anti-Gala,,Gal IgG (Gal) and specific IgM (M) and IgG (G) anti-T. cruzi reactivity. While the early phase was M+G-Gal-. the intermediate phase was M+G-Gal+, M+G+Gal-, or M+G+Gal+, and the late phase was M-G+Gal+. This sequence of stages was consistent with our previous studies on acute-phase proteins. Analysis by the polymerase chain reaction (PCR) of parasite DNA in 65 blood samples of children living in Cochabamba, Bolivia showed a significant correlation (90.8%) between ELISA and PCR positivity. A lower correlation was observed between indirect hemagglutination, PCR (58%), and ELISA. Electrocardiographic analysis of 43 children studied by the PCR did not show any alteration typical of acute chagasic myocarditis. The: PCR positivity was observed in eight samples where only Gal was increased, suggesting a very early T. cruzi infection, when specific antibodies were not yet present. By associating anti-Gal IgG with specific serology, early T. cruzi infection can be detected with greater precision. We suggest the use of anti-Gal antibody reactivity as an aid for the detection of recent T. cruzi infections, at least in endemic areas where diseases caused by other trypanosomatids do not overlap.