Transmission of HCV infection by RIBA indeterminate and positive blood units.

A retrospective study was carried out on the recipients of 73 units of blood from 53 donors found reactive for anti-HCV. The donors were screened with anti-HCV enzyme-linked immunosorbent assay (ELISA C-100) and reactivity was confirmed with the first generation recombinant immunoblot assay (RIBA I). Fifty-two patients were recipients of blood from donors reacting as RIBA I 'indeterminate' and 21 of blood from RIBA I 'positive' donors. Only three recipients (5.8%) from 'indeterminate' donors were anti-HCV positive indicating that such donors are very seldom infectious. Eleven (52.4%) recipients from 'positive' donors had antibodies to HCV, indicating that not all RIBA-positive donors are necessarily infectious. Pretransfusion samples of the seropositive recipients were unavailable. All samples were analyzed with the first generation ELISA and with either the second-generation ELISA or RIBA (RIBA II) in order to evaluate test sensitivity. RIBA II was more sensitive than RIB I. One RIBA I indeterminate donor was positive by RIBA II. His recipient had antibodies to HCV. Twelve RIBA I indeterminate and three RIBA I positive donors were negative by RIBA II. All their recipients were anti-HCV negative. The second-generation ELISA was also shown to be more sensitive than ELISA C-100. The second-generation ELISA detected six confirmed anti-HCV positive recipients who were negative by ELISA C-100.