Use of the recreational drug GHB and anal-brachial sex (fisting) were risk factors for infection with hepatitis C. However, there was no evidence of a hepatitis C epidemic amongst HIV-negative gay men. Preliminary findings of the study were presented to the International AIDS Conference in 2008. 

Since 2000, outbreaks of sexually transmitted hepatitis C have been reported amongst HIV-positive gay men across Europe as well as in New York. One city with a notable epidemic is Amsterdam. 

Investigators wished to obtain a better understanding of the prevalence of the infection and the risk factors for its acquisition. 

They therefore performed a cross-sectional study involving 689 gay men who attended a sexual health clinic in the city between 2007 and 2008. Individuals were tested for both HIV and hepatitis C and interviewed about their sexual and drug using behaviours. Phylogenetic analysis was also performed comparing the strains of hepatitis C detected in the men in the study to those circulating in HIV-positive gay men in Amsterdam between 2000 and 2007. 

Only two of the 532 HIV-negative men attending the clinic were infected with hepatitis C, a prevalence of below 0.5%. One of these men reported a history of injecting drug use. However, 28 of the 157 HIV-positive men were co-infected with hepatitis C, a prevalence of 18%. 

In 2007, prevalence of the infection amongst HIV-positive men was 15%, but this increased to 21% by the end of the study in 2008. Of the 28 HIV-positive gay men diagnosed with the co-infection during the study, seven (25%) had recently acquired the infection. 

The investigators’ first statistical analysis showed that infection with HIV, a greater number of life-time sexual partners, a history of sexually transmitted infections, unprotected anal intercourse, fisting, use of the drug GHB and a history of injecting drug use were all significantly associated with an increased risk of hepatitis C infection. 

However, subsequent analysis restricted to HIV-positive men found that only three of these factors were significant: injecting drug use (adjusted odds ratio [AOR]: 13.4; 95% CI, 1.56-115.7), fisting (AOR: 10.6; 95% CI, 2.78-40.7), and the use of GHB (AOR: 4.6; 95% CI, 1.62-13.0). 

Phylogenetic analysis revealed transmission clusters, with most of the new infections detected by the investigators located in a single cluster. 

“We found a high and increasing hepatitis C virus prevalence in HIV-infected men who have sex with men attending the Amsterdam STI clinic”, comment the investigators, who add “the relatively large proportion of acute infections strongly indicate a rapid and recent spread of hepatitis C virus among high-risk HIV-positive men who have sex with men.” 

Regarding the risk factors for hepatitis C infection, the investigators suggest “the practice of rough sexual techniques such as fisting, group sex and the sharing of sex toys might facilitate blood-to-blood contact by damaging the mucosal barrier.” 

A third of the men were unaware of their hepatitis C infection. Therefore all HIV-positive men are now offered hepatitis C testing at the clinic. 

The investigators conclude, “targeted preventions like raising awareness and internationally widespread routine testing are needed to minimize further spread among HIV-infected men who have sex with men, and spill-over into HIV negative men who have sex with men.”