Persons at Risk
Transmission of hepatitis C virus (HCV) through sexual contact appears to be uncommon, with prior studies showing transmission among long-term monogamous heterosexual partners occurring in less than 1% of couples per year. One recently published study estimated a maximum incidence rate of 0.7% per year among monogamous heterosexual couples, which corresponded to approximately one transmission per 190,000 sexual contacts. In contrast, reports have identified clusters of acute hepatitis C infection among men who have sex with men (MSM), primarily MSM who are also co-infected with HIV. Several other prospective cohorts and retrospective studies of HIV-infected persons or persons attending sexually transmitted diseases clinics have observed similar findings among HIV-infected MSM. Although ongoing injection drug use (IDU) remained the strongest risk factor for new HCV acquisition, several case control and cohort studies identified sexual contact as a potential source of transmission among HIV-infected MSM. HCV prevalence and incidence among non-IDU, HIV-negative MSM appears to still be low.
Factors Associated with Increased Risk of Sexual Transmission
For heterosexuals, having multiple sexual partners has been associated with an increased risk of HCV acquisition. Investigators have identified multiple risk factors associated with sexual transmission of HCV among MSM: (1) co-infection with HIV; (2) unprotected anal intercourse, especially as the receptive partner; (3) use of recreational drugs during sex, including gamma-hydroxybutyric acid (GHB) and methamphetamine; (4) co-incident ulcerative sexually transmitted diseases (lymphogranuloma venereum proctitis, syphilis); and (5) some sexual practices, including those that may result in bleeding or damage to genital mucosa, fisting, group sex, and use of shared sex toys.
Although the risk for sexually transmitting hepatitis C is extremely low (unless exhange of bloody fluids is involved), the consistent use of condoms is recommended during sexual activity to reduce the risk of other sexually transmitted diseases, including HIV and hepatitis B virus. Individuals with known hepatitis C should be counseled to discuss the risk of hepatitis C transmission, which is low but not zero, with their sex partners. The CDC has recommended that HCV-infected persons who have one long-term steady sex partner do not need to alter their sexual practices. Nevertheless, long-term partners should be offered the option of receiving HCV counseling and undergoing HCV testing. For HCV-discordant couples attempting to maximize reduction of the risk of HCV transmission, using latex condoms and avoiding sexual practices that potentially result in bleeding should presumably further reduce the risk of sexual HCV transmission. With growing evidence for sexual transmission of HCV among MSM engaging in higher risk sexual practices, it is particularly important to have an open conversation regarding sexual and drug-use practices to identify (1) HCV-negative persons at risk for HCV acquisition, and (2) HCV-infected persons who may engage in sexual practices that significantly increase the risk of HCV transmission to others.