Infection with hepatitis C virus genotype 4 in the United States

Hepatitis C virus genotype differences seem to be of considerable clinical significance because they affect responses to antiviral therapy. HCV genotype 4 is rare in the United States and there are few published data regarding response to therapy in patients with HCV genotype 4 infection.

To assess epidemiologic factors associated with HCV genotype 4 infection in United States and to describe the response rate to therapy with the combination of alpha interferon and ribavirin.

All hepatologists in our Division were asked for information about patients they had treated with HCV genotype 4. In addition, we searched the computer database from Saint Louis University Hospital in the last 40 months (1999 to 2002). Twenty HCV genotype 4 patients were identified. A retrospective chart review was performed to collect information about their demographics, risk factors for acquisition of infection, baseline laboratory studies and response to antiviral therapy.

A risk factor for exposure to HCV was noted in 14 cases (70%); 12 patients had a history of illicit drug use, whereas a history of blood transfusion was detected in three cases; 1 patient had both risk factors. Only 4 of 20 individuals had fibrosis stage 3 or 4 on liver biopsy. Seventeen patients were treated, 14 of whom completed therapy; 10 patients were sustained responders.

As with other HCV genotypes, most patients with HCV genotype 4 in the United States acquire the infection through intravenous drug use, liver disease is often mild to moderate in severity and 59% of our patients had a sustained virologic response after combination therapy with interferon and ribavirin.