[Seroprevalence of hepatitis C antibodies among blood donors. Study of second generation ELISA and RIBA tests and surrogate markers].

Between March and November 1991, prevalence of hepatitis C antibodies was evaluated in 60,960 blood donors from the North-East of France. Using a second generation ELISA, 424 donors (0.69%) were reactive, with no significant difference between males (0.69%) and females (0.70%). Among these 424 donors, respectively 137 (32.3%), 86 (20.3%) and 201 (47.4%) were reactive, indeterminate or nonreactive by a second generation RIBA (RIBA-2) (Recombinant Immunoblot Assay). Donors with a high ELISA ratio (> or = 4) were significantly more likely to have a reactive RIBA-2. Of the 1906 donors with anti-HBc positivity (3.12%), 44 had a reactive ELISA; of these, respectively 27, 12 and 5 had a reactive, indeterminate and nonreactive RIBA. Of the 1201 donors (1.97%) with increased serum ALAT (alanine-amino-transferase) levels (> or = 2N), 42 had a positive ELISA; of these, respectively 35, 2 and 5 had a reactive, indeterminate and nonreactive RIBA. Of the 54 donors with both indirect markers, nine had a reactive ELISA; the same nine donors had a reactive RIBA. These data show that donors with both surrogate markers and a reactive ELISA are very likely to have a positive RIBA. Seventy-seven (18.16%) of the 424 donors with a reactive ELISA had at least one surrogate marker; 67 of these donors (30.04%) were among the 223 donors with a reactive ELISA and a reactive or indeterminate RIBA.