Prevalence and risk factors for hepatitis C antibodies in volunteer blood donors in Brazil

BACKGROUND: Little is known about the prevalence, risk factors, and transmission of hepatitis C virus (HCV) in a nontransfused population, particularly in developing countries. STUDY DESIGN AND METHODS: To investigate the association between HCV seropositivity and some demographic variables, a case-control study was conducted on 138 seropositive donors among 4762 consecutive volunteer blood donors and 1101 seronegative controls in Rio de Janeiro, Brazil. Donors were initially screened by interview for male homosexuality, use of illicit drugs, tattoos, previous transfusions, venereal diseases, and jaundice. Eligible donors were then tested for HCV antibodies by enzyme-linked immunosorbent assay. A multivariate analysis was performed on age, ethnic group, gender, and prior donation. RESULTS: The overall prevalence of HCV seropositivity was 2.89 percent. An increased risk of seropositivity was demonstrated for nonwhite donors at an odds ratio of 2.11 (95% CI, 1.43-3.13), for males at 2.39 (95% CI, 1.01-5.7), and for prior donors at 1.66 (95% CI, 1.09-2.52). The risk of anti-HCV positivity increased markedly with age. Those at highest risk were the group 40 to 49 years old, with an odds ratio of 4.37 (95% CI, 2.39- 7.99) versus the group 20 to 29 years old. The group under 20 years old showed an odds ratio of 0.50 (95% CI, 0.06-3.87) compared to the group 20 to 29 years old. These findings were equally significant in a univariate analysis. CONCLUSION: Our results suggest that HCV seropositivity is strongly associated with male sex, nonwhite ethnicity, and greater age. A significant number of seropositive donors were not detected by screening interview.