Not a single case of sexual transmission of hepatitis C virus (HCV) was identified in a ten year study conducted amongst 171 Spanish heterosexuals who had a regular partner who was infected with both HIV and HCV. The study is reported in the April 2003 edition of the journal Sexually Transmitted Infections.
However, the same journal also reports an investigation conducted in Miami, Florida which found that having an HCV-positive sexual partner was a risk factor for acquiring the infection, and a case report of an HIV-positive man who became infected with HCV after sharing a treatment for erectile dysfunction which is administered by insertion into the urethra.
These studies look set to add to the debate about the sexual transmission of HCV, which is thought to occur at a higher rate amongst people infected with HIV. Evidence for this was recently the subject of a special issue of AIDS Treatment Update (link below).
Investigators in Madrid monitored 171 heterosexual couples, where one partner was positive for both HIV and HCV and the other negative, between 1991 and 2001. The same cohort of patients was monitored for oral transmission of HIV without a single case being attributable to this cause (see link below). At six monthly intervals both partners were interviewed sexually about their sexual behaviour. They were asked if they had had anal, oral, or vaginal sex and whether a condom had been used. Data on condom breakage or slippage were also obtained.
Over 529 person years of follow-up were counted and over 40,000 instances of anal or vaginal sex were reported. Sex without condoms was frequently reported by the couples in the study, with 43.3% reporting anal or vaginal sex without protection and a little under 70% oral sex without condoms. In addition, condom accidents were reported by 27% of study members.
Over 5,800 incidents of unprotected anal and vaginal sex were calculated to have occurred and unprotected oral sex was estimated ot have happened 25,000 times. Although 31 women became pregnant and one case of HIV seroconversion occurred, not a single case of HCV transmission could be identified. The investigators calculated that unprotected anal or vaginal sex had an HCV seroconversion rate of 0 to 6.3 per 10,000 unprotected intercourses and unprotected oral sex a rate of 0 to 1.4 per 10,000 intercourses.
The investigators conclude that “these results do not enable us to exclude the possibility of HCV transmission through sexual intercourse in heterosexual relationships, but do suggest that this transmission mechanism is inefficient, even when the index case is HIV co-infected.”
HCV amongst sexual health clinic patients in Miami
However, a study conducted amongst 687 people attending a sexually transmitted infections clinic in Miami, Florida found that along with injecting drug use and spending time in prison, sexual contact with an HCV infected person was a risk factor for becoming infected with HCV.
The study was conducted in early 2001, when clinic attendees were asked to complete a questionnaire about their demographic background and HCV risk activity. They were then tested for HCV, with 4.7% testing positive, which is consistent with rates of infection amongst sexual health clinic patients in the US.
Being aged over 30 and being a non-Hispanic white were the only demographic characteristics associated with HCV infection.
On univariate analysis, a history of injecting drug use, snorting drugs, having over 50 sexual partners, selling sex, spending at least a day in jail, household contact with an HCV-infected person, and sexual contact with an HCV-infected were all found to be associated with a greater risk of testing positive for HCV. Neither tattooing or body piercing, even if occuring in non-sterile environments were found to be related to an increased risk of HCV, even though these practices have been identified as modes of HCV transmission
When the results were subjected to multivariate analysis, only injecting drugs, spending a day or more in jail, sexual contact with an HCV-infected person, and older age remained associated with an increased risk of being HCV-positive. When sexual contact with an HCV-infected person was controlled for spending time in prison or injecting drug use, it was still found to be significantly associated with an increased risk of becoming infected with HCV.
HCV transmission from sharing a urethral injection
An unusual mode of sexual transmission of HCV is also reported in the same journal. The case concerns a 35 year old, gay, HIV-positive man in Brighton, UK, who was receiving HAART and was diagnosed with HCV in 2000 after abnormal liver function tests. The man denied injecting recreational drugs or steroids and reported consistent condom use. However, he did acknowledge a single instance when he shared a Caverject injection, a treatment for erectile dysfunction administered by insertion into the urethra, with his partner. Both men were found to be infected with the same strain of HCV. The investigators conclude that “it seems more than likely that transmission occurred via the shared Caverject needle”, adding, “users should be warned of the potential risk of transmission of HCV and other viruses including drug resistant HIV” if sharing Caverject.
Further information on this website
AIDS Treatment Update special – sexual transmission of HCV - September 2002 (pdf)
Hepatitis C - overview
Hepatitis C - factsheet
HIV and hepatitis - booklet in the information for HIV-positive people series (pdf)
Marincovich B et al. Absence of hepatitis C virus transmission in a prospective cohort of heterosexual serodiscordant couples. Sexually Transmitted Infections, 79: 160 – 162, 2003.
Weisbord JS et al. Prevalence and risk factors for hepatitis C virus infection among STD clinic clientele in Miami, Florida. Sexually Transmitted Infections, 79: 1-5, 2003.
Curtis S et al. A new way to catch hepatitis C. Sexually transmitted Infections, 79: 459, 2003.