Declining hepatitis C virus (HCV) prevalence in pregnant women: impact of anti-HCV screening of donated blood

BACKGROUND: Screening blood donors for hepatitis C virus (HCV) antibody has effectively mitigated transfusion transmission of HCV. We conducted a post hoc analysis to clarify the impact of donor screening on a general population of reproductive-age females and their offspring. STUDY DESIGN AND METHODS: Anti-HCV screening in Japan started in late-1989. In a cohort studied between May 1990 and November 2004, a total of 22,664 consecutive serum samples from pregnant women were screened for anti-HCV. Reactive samples were further tested for HCV RNA. Linear structural regression was applied to identify causal relationships. RESULTS: Anti-HCV-reactive rates declined significantly by two measures. First, among women known to have been transfused, rates fell from 14.8% to 3.1 % with the implementation of anti-HCV screening (p < 0.01). Nevertheless, this is 10 times higher than the 0.3% reactive rate seen in a similar cohort of non-transfused women. Second, rates fell from 1.8% among women born in 1955 or before to 0.3% for women born in 1966 or later (p < 0.01). Among 103 anti-HCV-reactive women, 31 (30%) had been transfused and another 17 (17%) had other identifiable risk factors. The remaining 55 (53%) had no clear risk factor. Blood transfusion accounted for 19% of anti-HCV acquisition, by path analysis. Only one infant in this cohort was vertically infected with HCV. CONCLUSION: Anti-HCV screening of donated blood and hygienic improvements have markedly decreased HCV infection of pregnant women with a transfusion history; however, 70% of anti-HCV-reactive women were deemed to be infected via routes other than transfusion.