Sexual transmission of hepatitis C virus (HCV) is taking place in HIV-negative as well as HIV-positive gay men, according to data from Brighton – the United Kingdom’s city of highest HIV prevalence – presented on Wednesday to the Fourteenth Conference on Retroviruses and Opportunistic Infections in Los Angeles.
In recent years there have been a number of studies reporting sexual transmission of HCV, primarily in HIV-positive gay men in western Europe. First observed in 2002in the UK, similar outbreaks have also been reported in the Netherlands, Switzerland and France.
Outbreaks of acute HCV infection amongst HIV-positive gay men (and other men who have sex with men [MSM] who may not identify as gay or bisexual) have been detected because HIV-positive people routinely undergo HCV antibody screening as well as regular liver function tests in order to monitor antiretroviral toxicity. However, HIV-negative gay men do not routinely receive such testing, so evidence of a possible parallel sexually transmitted HCV epidemic in this population has not been reported until now. Nevertheless, even the earliest reports from the UK included a small number of HIV-negative men.
Researchers from Royal Sussex County Hospital undertook a study to explore sexual transmission of HCV among HIV-positive and HIV-negative men attending Brighton’s main sexual health and HIV clinic between 2000 and 2006. Due to the high local HCV infection rate in this population, all MSM attending the clinic have been screened for HCV since 2000. Men were included in the analysis if they had one documented negative HCV antibody test and subsequently tested HCV antibody positive. Participants without a documented HIV antibody test results were classified as HIV status unknown. Men who reported injection drug use were excluded.
Out of a total of 7,169 clinic patients, 3,907 had at least one HCV antibody test, and 25 were newly diagnosed with HCV. Amongst this group, 16 were HIV-positive, five were HIV-negative, and four had an unknown HIV status.
HCV incidence increased from zero in 2002 to 1.4 per 1,000 patient years in 2003. Incidence increased in 2004 and 2005 to 1.6 and 1.9 per 1,000 patient years, respectively, and then jumped to 3.6 per 1,000 patient years in 2006.
HIV-positive men were found to be about thirteen times more likely to have a new HCV diagnosis compared with HIV-negative men. Dr Daniel Richardson, presenting, described the difference as “dramatic,” though the differences did not attain statistical significance due to the small numbers.
HCV incidence rates in HIV-negative men and those of unknown HIV status were similar.
In accordance with previous reports, incident HCV diagnosis was associated with fisting, unprotected anal intercourse, multiple sex partners, and infection with other sexually transmitted infections.
The researchers concluded there has been a significant increase in new HCV diagnoses amongst gay men attending their clinic, and – contrary to previous reports – these have not been seen exclusively in HIV-positive men. While HIV-positive serostatus remained a major risk factor for HCV infection, a substantial number of new infections occurred in HIV-negative men or those with unknown HIV serostatus.
Importantly, all but one of the nine men who were HIV-negative or had unknown HIV status at the time of their HCV diagnosis later went on to become infected with HIV, suggesting that they continued to engage in risky behaviour. Dr Richardson recommended that this high-risk group should be especially targeted for HIV prevention efforts. He also suggested that routine HCV antibody testing should be considered for all MSM, regardless of HIV serostatus.
Commentary and analysis
Brighton is a small city on England’s south coast, within easy reach of London. Despite its size, it has the highest concentration of gay men in the UK, and the UK’s highest HIV prevalence: last year, one in seven gay men in Brighton who agreed to anonymous HIV antibody testing were found to be HIV-infected. Last year, Dr Martin Fisher, a collaborator on the latest study, told AIDS Treatment Update that 8% of the gay men attending the city’s HIV clinic were already co-infected with HCV.
It is not clear why epidemics of sexually transmitted HCV in gay men have been observed in the UK and a few other western European countries, but not in North America. Studies involving HIV-negative gay men in Montreal and San Francisco have failed to find any evidence of sexual transmission of hepatitis C.
At the conference, Dr Fisher told aidsmap that outbreaks of sexually transmitted HCV may behave like classic sexually transmitted infections such as gonorrhoea or lymphogranuloma venereum (LGV), occurring in distinct, localised clusters.
Phylogenetic analysis from sexually transmitted HCV outbreaks amongst (mostly) HIV-positive gay men in London and Amsterdam has established that HCV transmission is primarily occurring within “hard” sexual networks. These and other reports suggest that many of the men in these networks regularly practice weekend-long sessions of fisting, unprotected anal intercourse and recreational drug use.
Such behaviour may also be occurring in other major cities, although studies exploring whether there are differences between European and North American sexual practices would shine some light on this. Dr Fisher indicated that he did not believe gay men in the UK and the US are that different, and that sexually transmitted HCV epidemics may occur elsewhere in the future. “I think [American cities] just haven’t seen it yet,” he told aidsmap. However, he also suggested that use of methamphetamine – a party drug of choice among gay men in the US – may have a different effect on HCV transmission than, for example, ecstasy or ketamine – the recreational drugs used more often in the UK.
The latest data refutes the assumption that sexual HCV transmission is likely to occur only in HIV-positive people. Brighton is the first city to present data following actively looking for incident HCV infection in HIV-negative and untested gay and bisexual men. However, other localities might observe similar results if they did the same. In particular, it remains unclear whether HIV-negative and untested men in the London (where men from Brighton often socialise) are also experiencing a new epidemic of sexually transmitted HCV.
Fisher M et al. Acute hepatitis C in men who have sex with men is not confined to those infected with HIV, and their number continues to increase. Fourteenth Conference on Retroviruses and Opportunistic Infections, Los Angeles, abstract 130, 2007.