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Serologic screening for Trypanosoma cruzi among blood donors in central Brazil
A L de Andrade1, C M Martelli, A O Luquetti
1Universidade Federal de Goiás, Instituto de Patologia Tropical e Saúde Pública, Brasil.
Insights
Blood banks in Brazil showed a 77% sensitivity in screening for Chagas disease (Trypanosoma cruzi) infection, with potential for infected transfusions. ELISA testing offered higher sensitivity at 96.3%.
Area of Science:
- Medical Parasitology
- Infectious Disease Epidemiology
- Blood Transfusion Safety
Background:
- Chagas disease, caused by Trypanosoma cruzi, is endemic in Central Brazil.
- Serological screening of blood donations is crucial for preventing transfusion-transmitted Chagas disease.
- Existing screening methods in blood banks may have variable efficacy.
Purpose of the Study:
- To compare the diagnostic performance of blood bank screening methods with a reference laboratory for Trypanosoma cruzi infection.
- To evaluate the efficacy of the ELISA technique for Chagas disease screening in a high-prevalence area.
- To assess the risk of transfusion-transmitted Chagas disease due to screening deficiencies.
Main Methods:
- Comparative analysis of serological test results from six Goiânia blood banks and a reference laboratory.
- Inclusion of 1,513 first-time blood donors from October 1988 to April 1989.
- Evaluation of indirect hemagglutination (IHA), complement fixation (CF), and enzyme-linked immunosorbent assay (ELISA) techniques.
Main Results:
- Blood banks demonstrated a relative sensitivity of 77% for Trypanosoma cruzi screening, with significant variability (50%-100%) between institutions.
- Twelve false-negative results were identified, indicating a risk of transmitting infected blood.
- ELISA achieved a sensitivity of 96.3% against the study's positivity standard, with 2 false negatives and 41 false positives when compared to IHA and indirect immunofluorescence (IIF).
Conclusions:
- Routine blood bank screening for Chagas disease in Goiânia exhibited suboptimal sensitivity, potentially allowing infected blood transfusions.
- The ELISA technique presents a more sensitive alternative for Chagas disease screening compared to traditional methods used by blood banks.
- Enhanced diagnostic strategies are necessary to improve blood safety and reduce the burden of transfusion-transmitted Chagas disease.
Abstract:
The study reported here compares results obtained by blood banks screening sera for chagasic (Trypanosoma cruzi) infection with results obtained by the Chagas' Disease Reference Laboratory of the Federal University of Goiás in Goiânia, Brazil. It also evaluates results obtained using the ELISA technique to screen the study sera. The survey used data from six of eight blood banks serving the city of Goiânia, an urban region of Central Brazil where Chagas' disease is highly endemic. The survey population consisted of 1,513 voluntary first-time blood donors whose donations occurred between October 1988 and April 1989. This group included 50% of all the first-time blood donors in that period. The six participating blood banks, which accounted for about 90% of all blood donations in Goiânia during the study period, routinely used indirect hemagglutination (IHA) and complement fixation (CF) tests to screen sera for antibodies to T. cruzi. Comparison of the results provided by the blood banks with the reference laboratory's results indicated a relative sensitivity of 77%, which ranged from 50% to 100% depending on the blood bank studied. The comparison, which found 12 false negative results, indicated that transfusions of infected blood might have occurred despite the serologic screening performed by the blood banks. Relative to the standard of positivity established for the study, the enzyme-linked immunosorbent assay (ELISA) technique was found to have a sensitivity of 96.3%. Considering as positive only those sera yielding positive IHA and indirect immunofluorescence (IIF) test results, the ELISA technique yielded 2 false negative and 41 false positive responses.(ABSTRACT TRUNCATED AT 250 WORDS)