ABSTRACT
Serologic diagnosis of Trypanosoma cruzi infection is important due to the limited sensitivity of direct parasitologic methods for diagnosis in the indeterminate and chronic phases of disease. SAPA antigen has been used in several studies and has been shown to be a good marker for use in the diagnosis of T. cruzi infection. Chagas disease and leishmaniasis are endemic in northern Salta with overlapping zones of transmission, which frequently leads to T. cruzi-Leishmania spp. mixed infections. Diagnosis is complicated by the fact that there is significant cross-reactivity when non-specific antigens are used. We evaluated the reactivity of GST-SAPA antigen in the ELISA test (ELISA-SAPA) against sera from persons infected with T. cruzi (n = 154), leishmaniasis (n = 66), mixed infections (29), and healthy controls (n = 28) using commercial ELISA and IHA kits as reference tests. For ELISA-SAPA the sensitivity, specificity and kappa index were calculated for detection of T. cruzi infection. Among sera from patients infected with leishmaniasis, 30.5% of co-infections were detected. ELISA-SAPA sensitivity was 97.1% (confidence interval 95%: 94.5-99.9), specificity was 100% (confidence interval 95%: 99.4-100), and kappa index was 96% (confidence interval 95%: 93-99%), for detection of T. cruzi infection. Sensitivity, specificity and kappa indices have shown a high efficiency of ELISA-SAPA.
Subject(s)
Antibodies, Protozoan/blood , Antigens, Protozoan , Chagas Disease/diagnosis , Glycoproteins , Leishmaniasis, Visceral/immunology , Neuraminidase , Trypanosoma cruzi/immunology , Antigens, Protozoan/immunology , Chagas Disease/immunology , Cross Reactions/immunology , Enzyme-Linked Immunosorbent Assay , Humans , Recombinant Proteins/immunology , Sensitivity and Specificity , Serologic Tests/methods , Species SpecificityABSTRACT
El diagnóstico serológico de la infección producida por Trypanosoma cruzi es de especial relevancia dado que los métodos parasitológicos tienen, en las fases indeterminada y crónica, una sensibilidad limitada. El antígeno SAPA fue usado en diversos estudios y demostró ser un buen candidato para el diagnóstico de la infección por T. cruzi. La enfermedad de Chagas y la leishmaniasis son endémicas en el norte de Salta, con posibles zonas de solapamiento. Este hecho suele dar lugar a infecciones mixtas T. cruzi-Leishmania spp., con la consecuente probabilidad de diagnóstico cruzado cuando se usan antígenos no específicos. Se evaluó la reactividad del antígeno GST-SAPA en la prueba de ELISA (ELISA-SAPA) frente a sueros de personas infectadas por T. cruzi (n = 154), con leishmaniasis (n = 66), infecciones mixtas (n = 29) y controles negativos (n = 28), usando como pruebas de referencia para el diagnóstico de la infección por T. cruzi kits comerciales de ELISA y HAI. Se calculó la sensibilidad, especificidad e índice de concordancia kappa de la prueba de ELISA-SAPA, para la detección de infección por T. cruzi. Entre los sueros de pacientes con leishmaniasis estudiados se detectó un 30.5% de infecciones mixtas. Para la detección de infección por T. cruzi, ELISA-SAPA mostró una sensibilidad del 97.1% (intervalo de confianza del 95%: 94.5-99.9), una especificidad del 100% (intervalo de confianza del 95%: 99.5-100) y un índice de concordancia kappa de 96 (intervalo de confianza del 95%:93-99%), comparado con las pruebas serológicas comerciales. Los valores de sensibilidad, especificidad y concordancia calculados muestran una alta eficiencia de ELISA-SAPA.
Serologic diagnosis of Trypanosoma cruzi infection is important due to the limited sensitivity of direct parasitologic methods for diagnosis in the indeterminate and chronic phases of disease. SAPA antigen has been used in several studies and has been shown to be a good marker for use in the diagnosis of T. cruzi infection. Chagas disease and leishmaniasis are endemic in northern Salta with overlapping zones of transmission, which frequently leads to T. cruzi-Leishmania spp. mixed infections. Diagnosis is complicated by the fact that there is significant cross-reactivity when non-specific antigens are used. We evaluated the reactivity of GST-SAPA antigen in the ELISA test (ELISA-SAPA) against sera from persons infected with T. cruzi (n = 154), leishmaniasis (n = 66), mixed infections (29), and healthy controls (n = 28) using commercial ELISA and IHA kits as reference tests. For ELISA-SAPA the sensitivity, specificity and kappa index were calculated for detection of T. cruzi infection. Among sera from patients infected with leishmaniasis, 30.5% of co-infections were detected. ELISA-SAPA sensitivity was 97.1% (confidence interval 95%: 94.5-99.9), specificity was 100% (confidence interval 95%: 99.4-100), and kappa index was 96% (confidence interval 95%: 93-99%), for detection of T. cruzi infection. Sensitivity, specificity and kappa indices have shown a high efficiency of ELISA-SAPA.
Subject(s)
Humans , Antibodies, Protozoan/blood , Antigens, Protozoan , Chagas Disease/diagnosis , Glycoproteins , Leishmaniasis, Visceral/immunology , Neuraminidase , Trypanosoma cruzi/immunology , Antigens, Protozoan/immunology , Chagas Disease/immunology , Cross Reactions/immunology , Enzyme-Linked Immunosorbent Assay , Recombinant Proteins , Recombinant Proteins/immunology , Sensitivity and Specificity , Species Specificity , Serologic Tests/methodsABSTRACT
We studied the seroprevalence of antibodies against Trypanosoma cruzi in the human population along with domiciliary infestation by triatomine bugs in an area endemic for Chagas disease in the Chaco Province of Argentina. In addition, we carried out parasitologic surveys in patients, dogs, wild mammals, and vectors. The mean seroprevalence in humans was 27.81% (109 of 392) and 24.14% (63 of 261) in 1-15-year-old children. The minimum domiciliary infestation rate was 13.33%, with certain areas reaching 53.85%. The prevalence was 15.09% (16 of 106) in dogs and 35.71% (10 of 28) in opossums. Infection with T. cruzi was detected in 30.10% (59 of 196) of the Triatoma infestans tested. Compared with nationwide studies, our data suggest that 1) there are zones requiring immediate sanitary action, and 2) nationwide estimates are based on very heterogeneous epidemiologic situations. This heterogeneity emphasizes the importance of in-depth studies of restricted areas to provide additional information for a better understanding of the present status of Chagas disease in Argentina.
