HIV Digest	HIV Digest Archive

Sexual transmission of hepatitis C virus between HIV-negative gay men is extremely rare, according to a Cana- dian study published last month. In an eight month period, only one in- cidence of hepatitis C virus serocon- version occurred in a cohort of over 1,000 gay men, and this case involved an individual who reported sharing injecting equipment in the previous six months.

There is considerable debate about the frequency of sexual transmission of hepatitis C virus, with epidemiological studies providing conflicting data. Studies in gay men have found a prevalence of hepatitis C virus antibodies ranging from 1% in Denmark to 7% in Italy. Recent studies have suggested an increased prevalence and incidence of hepatitis C virus infection in HIV-positive gay men, and it has been suggested that unprotected anal sex and fisting may be sexual activities which involve a significant risk of hepatitis C virus transmission in this population.

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In light of the conflicting data, investigators in Montreal examined the sexual transmission of hepatitis C virus in a cohort of 1054 gay men. This is the largest cohort of gay men which the sexual transmission of hepatitis C virus has been examined in. These men were enrolled in the Omega Cohort Study, an on-going prospective cohort into the risk factors of HIV transmission amongst gay men in Montreal.

A detailed questionnaire, inquiring about sexual activity, and possible routes of hepatitis C virus transmission (blood transfusion, injecting drug use, snorting drugs, and less likely routes such as tattooing and body piercing) was completed by all the men.

Median age was 32 years, and the men in the study had extensive sexual experience. In total, 92% of men reported anal sex at sometime with either a regular or casual partner and 63% of men said that they had had unprotected anal sex with either a regular or casual partner. Over 40% of men said that they had had 50 or sexual partners in their lifetime, and 37% said that they had had unprotected anal sex with a casual partner. In addition, 44% of men said that they had had five or more regular partners in their lifetime and 56% said that they had had unprotected anal sex with a regular partner.

Of the 1085 men who participated in the study, 32 were hepatitis C virus antibody positive (3%). Of these, it was found that 31 were already infected at baseline. The remaining individual seroconverted between the first and second follow-up visits.

When the investigators looked at the hepatitis C risk activities of the 31 men who had antibodies to the virus at baseline, they found that 20 were current injecting drug users, eight were former injecting drug users and three had no reported history of injecting drug use. Therefore, the prevalence of hepatitis C virus amongst the 980 gay men in the study with no reported history of injecting drug use was 0.3%.

Hepatitis C virus prevalence was much higher amongst current injecting drug users (48%) than former injecting drug users (20%,), and unsurprisingly was also higher amongst drug users who reported sharing needles than those who had never shared needles (48% versus 13%).

After controlling for injecting drug use, sexual behavior (including number of regular or casual partners, and unprotected anal sex with both types of partners) was not significantly associated with prevalent hepatitis C virus infection.

The investigators examined in more detail the sexual behavior of the three non-injecting drug users with hepatitis C virus. They found that their sexual behavior did not differ significantly from the hepatitis C virus antibody negative men. Indeed, two of the three men said that they had used condoms 100% of the time. One man said he had had a blood transfusion and a body piercing and the other two reported cocaine snorting and body piercing.

"The 1085 men who were hepatitis C virus negative at baseline contributed a total of 2653 person-years of follow-up. With only one seroconversion, the overall incidence of hepatitis C virus seroconversion was 0.038 per 100 person years", write the investigators.

Regarding this single seroconversion, the investigators note, "this seroconversion occurred in an injecting drug user who reported needle sharing during the six months preceding the visit at which he first tested positive for hepatitis C virus."

Editor's Note: from www.aidsmap.com