Thursday, January 22, 2009

The Difficulties of Acute HCV-Infection Diagnosis

Most individuals infected with hepatitis C virus (HCV) fail to clear virus at the acute stage, becoming chronically infected, with consequent significant risks of progressive liver disease, cirrhosis and hepatocellular carcinoma. Treatment of chronic HCV with combination pegylated-interferon (PEG-IFN) and ribavirin achieves sustained virological response (SVR) rates of 42-52% of patients infected with HCV genotype 1 and 76-82% of those with genotype 2/3. In contrast, much higher SVR rates (e.g. >97%) have been reported when treating acute HCV infection with PEG-IFN, irrespective of the infecting genotype. It would thus seem preferable to treat HCV infection at the acute stage rather than waiting for the infection to become chronic.
The problem is the diagnosis of acute HCV infection is not straightforward. Detection of anti-HCV IgM does not distinguish acute from chronic infection. Genome or antigen detection techniques provide information on the current infection status of an individual, but do not indicate when infection may have taken place. One possible laboratory approach to diagnosis of acute infection would be to demonstrate sero- or genoconversion in serial samples, but practically, it is difficult to obtain regular repeat samples in high-risk individuals such as injecting drug users (IDUs). Clinical approaches to diagnosis are also flawed. Only a small minority of acute infections are symptomatic. Even in patients presenting with acute hepatitis C, the majority of whom are already anti-HCV positive, one cannot be certain that illness is due to recent infection with HCV rather than another inter-current cause in a chronically infected patient.
(J Viral Hepat. 2008;15(12):871-877)