Serological tests are the main laboratory procedures used for diagnosis during the indeterminate and chronic stages of Chagas' disease. A serological regression to negativity is the main criterion used to define parasitological cure in treated patients. The aim of this work was to monitor the individual specificities of antibody levels for 3 years posttreatment in 18 adult patients. Conventional serological techniques (hemagglutination assays and enzyme-linked immunosorbent assay [ELISA]) were modified by using recombinant antigens to detect early markers of treatment effectiveness. For this purpose, serum samples were taken before and during treatment and every 6 months after treatment for at least 3 years. When hemagglutination assays were used, a decrease in antibody levels was observed in only one patient. When ELISA with serum dilutions was used, antibody clearance became much more apparent: in 77.7% (14/18) of the patients, antibody titers became negative with time. This was observed at serum dilutions of 1/320 and occurred between the 6th and the 30th months posttreatment. The immune response and the interval for a serological regression to negativity were different for each patient. For some of the recombinant antigens, only 50% (9/18) of the patients reached the serological regression to negativity. Recombinant antigen 13 might be a good marker of treatment effectiveness, since 66.6% (six of nine) of the patients presented with an early regression to negativity for specific antibodies to this antigen (P ؍ 0.002).
HighlightsThis is the first meta-analysis of individual data in chronic Trypanosoma cruzi infection after treatment.The probability of seroreversion is variable along the course of follow-up.An interaction was found between age at treatment and country setting.The course of parasitological/molecular tests after treatment needs to be assessed.
recomienda controlar la eficacia terapéutica con pruebas serológicas y parasitológicas convencionales. Sin embargo las primeras suelen continuar positivas 10 años o más luego del tratamiento, y las segundas son, en general, de baja sensibilidad en esta etapa de la enfermedad. La Reacción en Cadena de la Polimerasa (PCR) al ser más sensible que los exámenes parasitológicos convencionales, podría informar con una cobertura mayor si hubo falla terapéutica. Hemos ofrecido tratamiento con benznidazol (5 mg/kg/ día, por 60 días) a 138 pacientes de 16 a 35 años de edad, infectados crónicamente con Trypanosoma cruzi. La eficacia terapéutica se controló con PCR periódicas, hemocultivo y serología convencional en dos grupos de pacientes: uno (GT, 57 pacientes) que aceptó y cumplió el tratamiento y otro (GNT, 37 pacientes) que lo rechazó. Antes de la administración de benznidazol la PCR mostró una sensibilidad diagnóstica de 41% (57/138 pacientes) y el hemocultivo 7,2% (10/138). Sesenta meses postratamiento el grupo GT mostró una positividad de PCR acumulada de 28,1% (16/57) y el grupo GNT 54,1% (20/37; p=0.0016). A pesar de que la sensibilidad diagnóstica de PCR es limitada, la negatividad de pruebas repetidas con método normatizado podría evidenciar disminución de la parasitemia o probable curación en 71,9% de los pacientes tratados, lo que habría que confirmar con el seguimiento serológico.PALABRAS CLAVE: Enfermedad de Chagas; reacción en cadena de la polimerasa; benznidazol; tratamiento específico; diagnóstico serológico
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