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| Clinical Background: |
Acute infection with HCV is frequently asymptomatic, and the majority of patients (70-80%) develop chronic HCV infection after failing to clear the virus. While most of these patients will have a mild, protracted and slowly progressing course, 15-20% progress to serious end-stage liver disease, most critically, cirrhosis.
Given the number of individuals predicted to harbor active infection in the US (4 million, 100 million worldwide), and the relative silence of both the acute and chronic process, blood banking has been significantly affected by the virus. Identification of HCV carriers, including those who have been recently infected but have not seroconverted is vital to maintainance of blood bank integrity. Serologic tests for HCV have several limitations. Diagnosis of acute HCV infection using serology is difficult because seroconversion can take as long as 22 weeks. In addition, more than half of blood donors who are reactive for anti-C100 (a recombinant non-structural protein from HCV) are probably false positives. Lastly, equivocal positive results occur with enzyme immunoassay (EIA) methodology; confirmatory assays such as the four antigen recombinant immunoblot assay (RIBA) are of limited utility in resolving these results. Highly sensitive assays that detect HCV RNA indicate active infection and therefore have better performance characteristics (greater sensitivity and specificity) than serology. |
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