Abstract
Chagas disease (CD) is among the top 10 causes of inability to blood donation. Blood donation centers screen for anti-Trypanosoma cruzi antibodies using highly sensitive immunoenzymatic (ELISA) or chemiluminescent methods, which can lead to false positive results. Since positive samples cannot be used, to avoid the loss of valuable blood donations, it is necessary to improve specificity without reducing the sensitivity of the tests used for blood screening. For this purpose, our group has developed four chimeric proteins (IBMP-8.1, IBMP-8.2, IBMP-8.3, and IBMP-8.4) that have been evaluated in phase I and II studies with high performance and low cross-reactivity rates. The study included a panel of 5,014 serum samples collected from volunteer blood donors at the Hematology and Hemotherapy Foundation of the State of Bahia (Brazil). They were subjected to the detection of anti-T. cruzi antibodies, using all four IBMP antigens individually and latent class analysis (LCA) as a reference test, since there is no gold standard test for this purpose. Considering the sample size analyzed, LCA classified 4,993 (99.6%) samples as T. cruzi-negative and 21 (0.42%) as T. cruzi-positive. Sensitivity values ranged from 85.71% for IBMP-8.1 and 90.48% for IBMP-8.2–95.24% for IBMP-8.3 and 100% for IBMP-8.4, while specificity ranged from 99.98% for IBMP-8.3 and IBMP-8.4–100% for IBMP-8.1 and IBMP-8.2. Accuracy values ranged from 99.4 to 99.98%. The pretest probability for the molecules was 0.42, whereas the positive posttest probability ranged from 95.24 to 99.95% and the negative posttest probability ranged from 0.00001 to 0.0006% for all antigens. The higher odds ratio diagnosis was found for IBMP-8.4, which has been shown to be a safe single antigen for serological screening of CD in blood samples. The use of chimeric IBMP antigens is an alternative to reduce the number of bags discarded due to false-positive results. These molecules have high diagnostic performance and were shown to be suitable for use in screening CD in blood banks, isolated (IBMP-8.4) or in combination; and their use in blood banks could significantly reduce unnecessary disposal of blood bags or the risk of T. cruzi transmission.
Highlights
Human Chagas disease (CD) or American trypanosomiasis is a life-threatening, neglected tropical parasitic disease caused by the hemoflagellate protozoan Trypanosoma cruzi
We evaluated the performance of the chimeric antigens for serological screening of CD and their potential use in blood banks
All four IBMP antigens showed high diagnostic capacity based on the area under the ROC curve (AUC) values found, which ranged from 98.68 to 100%, suggesting high discriminatory ability
Summary
Human Chagas disease (CD) or American trypanosomiasis is a life-threatening, neglected tropical parasitic disease caused by the hemoflagellate protozoan Trypanosoma cruzi. Approximately 6 million people in 21 Latin American countries are affected by CD and 7,500 CD-associated deaths are reported annually [1]. Due to constant presence of the vector, 65 million people in these regions are at risk of infection [1]. Other routes of transmission such as blood transfusion, organ donation, consumption of contaminated food or beverages, and mother-tochild transmission represent increasingly important alternative routes of infection [2, 3]. Since the late 1990s, demographic shifts and migration flows have fueled the spread of T. cruzi-infected individuals worldwide, in non-endemic countries in North America, Europe, and Oceania [4–6]. Due to the lack of universal donor screening to exclude CD in blood banks, transmission through contaminated blood transfusions accounts for nearly 20% of new cases annually worldwide [7]
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