IAS: Rectal trauma and drug use key in sexual transmission of HCV

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The factors involved in the sexual transmission of hepatitis C virus amongst HIV-positive gay men may be more complex than previously thought, according to German research presented to the recent 4th International AIDS Society Conference in Sydney.

Investigators from Bonn initially found, in common with several other recent studies, that unprotected anal intercourse was associated with a risk of hepatitis C. But in subsequent statistical analysis, only snorting drugs and rectal bleeding after sex were risk factors for infection with hepatitis C. The study’s researchers fear that hepatitis C prevention that focuses only on consistent condom use could be too narrow in its cope and overlook potentially more important risk behaviours.

Doctors from across Europe have been observing mini-epidemics of hepatitis C virus in HIV-positive gay men. Several studies have implicated unprotected anal sex as a significant risk factor for the sexual transmission of hepatitis C, with other research showing an association with fisting, drug use and some sexually transmitted infections.



The last part of the large intestine just above the anus.

multivariate analysis

An extension of multivariable analysis that is used to model two or more outcomes at the same time.

unprotected anal intercourse (UAI)

In relation to sex, a term previously used to describe sex without condoms. However, we now know that protection from HIV can be achieved by taking PrEP or the HIV-positive partner having an undetectable viral load, without condoms being required. The term has fallen out of favour due to its ambiguity.


In medical terms, going inside the body.


In a case-control study, a process to make the cases and the controls comparable with respect to extraneous factors. For example, each case is matched individually with a control subject on variables such as age, sex and HIV status. 

Although few would seriously doubt that hepatitis C is being sexually transmitted between HIV-positive gay men, there is, nevertheless, very little evidence of sexual transmission of the virus in HIV-negative gay men, or in HIV-positive heterosexual couples. Although one study found that hepatitis C was more likely to be found in the semen of those with HIV, therefore explaining transmission of the virus via unprotected sex, some investigators believe that the factors involved in the sexual transmission of hepatitis C may be much more complex.

To try and obtain a better understanding of the sexual, behavioural and social risk factors for the sexual transmission of hepatitis C amongst HIV-positive gay men, investigators in Germany conducted a case-controlled study in late 2006. Each HIV-positive gay man diagnosed with hepatitis C was matched with two HIV-positive, but hepatitis C-uninfected gay men.

The investigators then obtained demographic data as well as information on sexual behaviour and the use of recreational drugs. Men were also asked to say if they had received blood products or had had an invasive medical procedure, a tattoo or body piercing, as these are possible modes of hepatitis C transmission if screening and sterilisation procedures are not adhered to.

A total of 22 cases and 44 controls were recruited to the study. In bivariate analysis, snorting drugs (OR = 10.5), a history of major surgery (OR = 9.1), unprotected anal sex with more than five men in the previous year (OR = 7.5), bleeding from the rectum after sex (OR = 7.1), fisting (OR = 5.9), and use of erectile dysfunction drugs (OR = 4.1) were all significantly associated with an increased risk of being infected with hepatitis C.

But in subsequent multivariate analysis, most of these factors ceased to be significant. Only snorting drugs (OR = 13.5, p

“Unprotected anal intercourse per se does not sufficiently explain hepatitis C transmission among HIV-positive men who have sex with men”, write the investigators.

They add, “the possibility of hepatitis C coinfection is frequently used to encourage HIV-positive men who have sex with men to consistently use condoms, and condom use seems to be the predominant focus in hepatitis C prevention messages for men who have sex with men. We fear in this narrow perspective, other and possibly more effective hepatitis C prevention messages could be neglected.”

Group sex and anal trauma are highlighted by the investigators as factors potentially implicated in the sexual transmission of hepatitis C. They note that 46% of cases, but only 10% of controls, reported group sex, and that anal bleeding after sex was much more common in cases than controls (27% versus 5%). The use of sex toys, fisting, or longer duration and frequency of anal intercourse due to the use of erectile dysfunction drugs could all, the researchers believe, contribute to an increased risk of anal bleeding.

The investigators also believe that there is an important role for recreational drug use in the sexual transmission of hepatitis C. They note that nasal and rectal administration of drugs can cause ulceration that can facilitate the transmission and acquisition of hepatitis C. Furthermore, drug use can increase the duration and intensity of sex, meaning there is a greater risk of rectal injury.

“Prevention efforts are needed to communicate sexual or sex-associated routes of transmission for hepatitis C that cannot be prevented by condoms alone”, conclude the investigators.


Schmidt AJ et al. Risk factors for hepatitis C in HIV-positive MSM. A preliminary evaluation of a case control study. Fourth International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention, abstract MOPEB037, Sydney, 2007.