Prevalence of hepatitis C virus antibodies in Sydney blood donors.

OBJECTIVE: To determine the prevalence of hepatitis C virus (HCV) antibodies in the Sydney blood donor population. DESIGN: All blood donations collected from Red Cross blood donors in Sydney from February 1990 until April 1991 were tested for HCV antibodies. For those samples found reactive in an anti-HCV screening test, a confirmatory test was carried out for the presence of HCV antibodies and the alanine aminotransferase level was measured. RESULTS: The prevalence of repeated reactivity to the screening test was 0.45% among blood donations overall, and 1.02% in donors giving blood for the first time in the study period. The confirmatory test result was positive for 30.8% of donations found to be repeatedly reactive in the screening test. There was little change over the study period in the HCV antibody prevalence of donors giving blood for the first time, but there was a clear decrease in the prevalence among all donations. Prevalence in males was nearly twice the prevalence in females--a difference which was consistent across age groups. The highest prevalence in both sexes was in the age group 30-34 years. Among samples for which the screening test results was positive, there was a strong correlation between the reactivity recorded for the screening test and both the proportion found positive by the confirmatory test and the proportion with an elevated alanine aminotransferase level. CONCLUSION: The small proportion of blood donations found to be repeatedly reactive by anti-HCV screening and the relatively good correlation with the confirmatory test and liver function assay indicate that a policy of discarding these donations will decrease the risk of transfusion-transmitted HCV infection without materially affecting the supply of blood.