Among 248 asymptomatic blood donors positive for anti-widespread in the blood donor population, that hepatitis C accounted for more than 90% of transfusion-transmitted body to hepatitis C virus (anti-HCV) enrolled in a long-term prospective study, 86% had chronic HCV infection and 14% hepatitis, and that chronic HCV infection, although generally asymptomatic, could in some cases lead to cirrhosis, hepato-appeared to have recovered as assessed by serial determinations of serum alanine aminotransferase (ALT) levels and cellular carcinoma (HCC), and end-stage liver disease. 2,3 First-generation tests for anti-HCV were introduced into HCV RNA by polymerase chain reaction. Established parenteral risk factors for HCV transmission were identified in blood donor screening in 1990. At that time, 0.5% to 0.6% of donors were repeatedly reactive by enzyme immunoassay 75% of donors. In addition, there was a strong independent association between HCV positivity and cocaine snorting, sug-(EIA), and approximately 0.3% could be confirmed as positive by supplemental strip recombinant immunoblot assay. gesting that shared snorting devices may be a covert route of parenteral transmission. Ear piercing in males was also More sensitive second-and third-generation EIAs 4 were introduced in 1992 and 1996, respectively. Current data from significantly associated with transmission. There was no evidence for sexual spread. Although the majority of HCV carri-the American Red Cross indicate that 0.23% of blood donors now test repeatedly positive for anti-HCV, and 0.16% can be ers had both biochemical and histological evidence of chronic viral hepatitis, the extent of liver injury was generally mild. confirmed by supplemental assays. These tests have been extremely effective in the prevention of transfusion-associ-Among a larger population of 280 HCV RNA-positive donors, 17% had repeatedly normal ALT levels, 45% had levels that ated hepatitis. An ongoing prospective study of transfusion recipients at the Clinical Center of the National Institutes did not exceed twice, and only 22% had levels that exceeded five times the upper limit of the normal range. Among 81 of Health (NIH) has shown no cases of hepatitis C among approximately 650 recipients monitored since second-gener-patients who underwent liver biopsy, only 13% had evidence of severe hepatitis (8%) or cirrhosis (5%), despite a duration ation EIA screening was implemented.
Screening assays for anti-HCV have uncovered a large of infection that generally exceeded 15 years. No severe histological lesions were observed in blood donors with chronic group of patients who are asymptomatic HCV carriers. Population-based surveys suggest that there are almost four mil-HCV infection who had repeatedly normal ALT levels. In both donors and blood recipients, the frequency of severe lion HCV carriers in the United States. Furthermore, this virus is globally distributed, with anti-HCV rates among do-morbidity or mortality related to HCV infection was less than 10% during the first two decades of infection. Further long-nors throughout the world ranging from 0.3% to 1.5%. Thus, hepatitis C has been found to be a common infection of term studies are required to see if the progression to severe outcomes continues to accrue at this slow pace or whether it worldwide importance.
What is the significance of this infection to these asymp-accelerates during subsequent decades. (HEPATOLOGY 1997; 26(Suppl 1):29S-33S.) tomatic individuals? How were they infected? What is the risk that they will transmit the infection to others? What proportion of antibody-positive individuals have viremia and The cloning of the hepatitis C virus (HCV) 1 and subsechronic infection? What proportion have significant liver disquent development of sensitive serologic assays for antibody ease? What insights can we derive from this asymptomatic to HCV (anti-HCV) and reliable polymerase chain reaction donor population in assessing the natural history of HCV (PCR) tests for HCV RNA have shown that this agent is infection? In the spectrum of HCV associated disorders, what proportion are represented by the relatively benign disease seen in donors and what proportion progress to the severe Abbreviations: HCV, hepatitis C virus; anti-HCV, antibody to hepatitis C virus; outcomes that now make HCV-related liver failure the lead-PCR, polymerase chain reaction; HCC, the hepatocellular carcinoma; EIA, enzyme ing indication for liver transplantation in adults? To address immunoassay; NIH, National Institutes of Health.
these issues, we review data from an ongoing NIH study of From the