The sexual partners of men with hepatitis C virus (HCV) infection have a relatively low prevalence of the disease, yet cases of sexual transmission have been reported. With the discovery of a new HCV-related virus named hepatitis G (HGV) or GBV-C, the issue of sexual transmission has become more complicated. It is now recognized that HGV and GBV-C are two distinct isolates of the same virus, to be labeled HGV/GBV-C. Previous studies indicate that HGV/GBV-C infection may occur in up to 7 percent of the population and may infect up to 30 percent of persons at risk for bloodborne infections, such as intravenous drug users. Semprini and colleagues examined semen and serum samples from men infected with hepatitis C to determine whether HCV RNA and HGV/GBV-C RNA are present in semen.

The 90 men in the study were former intravenous drug users. All tested positive for anti-HCV antibodies. Of the group, 27 were also positive for human immunodeficiency virus (HIV) infection, and 10 were positive for hepatitis B surface antigen. All of the men were asymptomatic, and none were receiving antiviral medication. The semen and serum samples were tested for HCV and HGV/GBV-C RNAs by polymerase chain reaction, hybridization and sequence analysis. Although 56 patients had detectable serum HCV RNA, none of the 90 men had HCV RNA in their semen.

HGV/GBV-C was detected in the serum of 28 of the 90 men. Seventeen of these 28 men were also HCV RNA positive; eight of the 17 were also HIV positive. HGV/GBV-C RNA sequences were detected in seminal plasma in six of 12 samples free from polymerase chain reaction inhibitors.

The authors suggest that reports of infection of sexual partners of men with hepatitis C may represent cases of HGV/GBV-C infection. Alternatively, hepatitis C could be transmitted during sexual activity by blood from minor abrasions or other lesions. Seminal fluid alone does not appear to pose a significant risk in the transmission of hepatitis C. The findings also suggest that a significant number of men infected with HCV may also be infected with HGV/GBV-C, which can pose a threat of sexual transmission.