[Serological screening for Trypanosoma cruzi among blood donors in central Brazil]. / Triagem sorológica para o Trypanosoma cruzi entre doadores de sangue do Brasil central.

The present study compares the results of serological screening for Trypanosoma cruzi infection done at blood banks with results obtained in Chagas' disease studies undertaken by the Reference Laboratory of the Federal University of Goiás (UFG) and evaluates the use of the enzyme-linked immunosorbent assay (ELISA) for this purpose. The study was conducted with data from six of the eight blood banks in the city of Goiânia in central Brazil, an urban area in which this infection is highly endemic. The population studied consisted of 1,513 volunteers who had donated blood for the first time between October 1988 and April 1989. The sample represented 50% of all first-time blood donors during the period. Of these donors, 94% were residents of urban areas, and of these, approximately 26% had migrated from the countryside. Nearly 90% of the blood donations in the city are received at these banks, which normally use the indirect hemagglutination and complement-fixation tests. The samples selected for the study of T. cruzi antibody in first-time blood donors were assayed at the Reference Laboratory of the Federal University of Goiás using the indirect hemagglutination (IH), indirect immunofluorescence (IF), and enzyme-linked immunosorbent assay (ELISA) tests, independently of the serological classification performed by the blood banks. Comparison of the results provided by the latter with the positivity pattern established in the study (IH and IF yielded simultaneous positive results in the Reference Laboratory) revealed a relative sensitivity of 77%, with extremes ranging between 50% and 100%, depending on the blood bank studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Serologic screening for Trypanosoma cruzi among blood donors in central Brazil.

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)