ABSTRACT
INTRODUCTION: Serological cross-reactivity between leishmaniasis and Chagas disease, especially at low titers, leads to difficulties of the seroepidemiological interpretation. METHODS: We have studied the ability of urea as a chaotrope to select high-avidity antibodies in IgG ELISA, thus reducing low-avidity IgG cross-reactivity in serologically positive samples in both assays. RESULTS: Using 0.5M urea for diluting the sample efficiently defined leishmaniasis or double infections in high-avidity IgG ELISA and eliminated false-positive results. CONCLUSIONS: The use of a chaotropic diluting agent is useful for improving the specificity of Chagas disease and leishmaniasis immunoassays.
Subject(s)
Antibodies, Protozoan/blood , Antibody Affinity/immunology , Chagas Disease/immunology , Cross Reactions/immunology , Immunoglobulin G/blood , Leishmaniasis/immunology , Urea/pharmacology , Biomarkers/chemistry , Brazil/epidemiology , Chagas Disease/complications , Chagas Disease/diagnosis , Chagas Disease/epidemiology , Enzyme-Linked Immunosorbent Assay , Humans , Leishmaniasis/complications , Leishmaniasis/diagnosis , Leishmaniasis/epidemiology , Population Surveillance , Sensitivity and Specificity , Urea/chemistryABSTRACT
Abstract INTRODUCTION: Serological cross-reactivity between leishmaniasis and Chagas disease, especially at low titers, leads to difficulties of the seroepidemiological interpretation. METHODS: We have studied the ability of urea as a chaotrope to select high-avidity antibodies in IgG ELISA, thus reducing low-avidity IgG cross-reactivity in serologically positive samples in both assays. RESULTS: Using 0.5M urea for diluting the sample efficiently defined leishmaniasis or double infections in high-avidity IgG ELISA and eliminated false-positive results. CONCLUSIONS: The use of a chaotropic diluting agent is useful for improving the specificity of Chagas disease and leishmaniasis immunoassays.