- Category: HIV/HCV Coinfection
- Published on Friday, 03 August 2012 00:00
- Written by Liz Highleyman
The decade-long outbreak of sexually transmitted hepatitis C virus (HCV) infection among HIV positive men who have sex with men in Amsterdam appears to have leveled off since 2007, perhaps due to increased testing and treatment, but more education and screening are needed, researchers reported at the XIX International AIDS Conference (AIDS 2012) last week in Washington, DC
Public health officials have traditionally thought that HCV is not commonly transmitted through sex, based on studies of monogamous heterosexual couples. But outbreaks of presumably sexually transmitted hepatitis C among HIV positive gay and bisexual men were first reported in the U.K. around 2000, then in large continental European cities, and later in Australia and the U.S. as well.
HCV is transmitted through blood -- little or none is found in semen -- and it is hardier and can live longer outside the body than HIV. The risk factors for sexual transmission of HCV are not well understood. Increased risk has been linked to sexual practices including anal intercourse and fisting, having other sexually transmitted infections (STIs), and recreational drug use, but specific predictors vary from study to study. Determining risk factors is difficult in part because most people do not engage in only a single sexual activity or other risk behavior.
These outbreaks have almost exclusively involved HIV positive MSM and a few HIV positive women -- including people with high CD4 T-cell counts. There is ongoing controversy about whether liver disease progresses especially rapidly in people who are already HIV positive when they contract HCV (among injection drug users, HCV infection usually occurs first).
Anouk Urbanus from the Amsterdam Public Health Service presented a 15-year overview of one of the first and most closely watched of the sexually transmitted hepatitis C epidemics.
Gay and bisexual men attending a large sexual health clinic in Amsterdam participated in bi-annual cross-sectional anonymous surveys between 1995 and 2010. The men were interviewed about behavioral risk factors and tested for HIV and HCV antibodies. Everyone with a positive antibody test and all men with HIV also received HCV RNA tests, as people with compromised immunity may not produce enough antibodies to show up on a standard screening test.
The researchers looked at risk factors associated with HCV infection. They ran their analyses with fisting and use of the club drug GHB excluded, as these were highly interrelated.
They also performed phylogenetic analysis of the HCV NS5B gene sequence to determine HCV genotypes and to characterize relationships among individual viral strains, which provides information about how the virus spreads within social and sexual networks.
The present analysis included 777 HIV positive and 1513 HIV negative MSM. The median age was 40 years, about 70% were born in the Netherlands, and only 3.5% reported ever injecting drugs.
- HCV antibody prevalence -- or total cases -- among HIV positive MSM gradually increased from 2.8% in 1995 to 3.8% in 2003.
- Prevalence then increased at a steeper rate, reaching a peak of 17.3% in 2008. In contrast, HCV prevalence among HIV negative MSM remained stable, at around 0.5%.
- HCV incidence -- or new cases -- among HIV positive MSM was highest in 2006, at 14.0 per 100 person-years.
- Incidence decreased somewhat thereafter, but not significantly.
- In 2007-2008 fisting was found to have a stronger association with HCV infection than it did in 2009-2010 (odds ratios [OR] of 2.85 vs 1.06, respectively).
- Other risk factors independently associated with HCV infection, in the analysis that excluded GHB use, were:
o Unprotected anal sex (OR 5.01, or 5 times higher risk);
o History of injection drug use (OR 5.21);
o Chlamydia (OR 2.27, or more than twice the risk);
o Older age (OR ranging from 2.16 to 4.17 for older age groups relative to those under 35 years).
- Risk factor associations were generally similar in the analysis that excluded fisting, except that the OR for unprotected anal sex fell to 2.63.
- Phylogenetic analysis revealed a high degree of clustering specifically within networks of gay and bisexual men from 2000 onwards; only 1 cluster included an HIV negative man.
- The most recently detected cluster included an acute or recent infection, indicating that transmission is still happening.
"HCV prevalence among HIV positive MSM significantly increased until 2007, but appears to be leveling off in recent years," the researchers concluded.
They suggested this trend might be explained by reduced risk behavior, earlier testing, more hepatitis C treatment, and "saturation" within the population at highest risk. Urbanus also explained that STI clinic staff and HIV specialists had increased educational efforts about HCV transmission.
Both risk factor analysis and phylogenetic analysis continue to point to ongoing sexual transmission of HCV among HIV positive gay and bisexual men, the researchers added, noted that HIV negative men also engaged in similar types of sexual activity and drug use but were not becoming HCV-infected.
They recommended that monitoring of HCV prevalence and incidence in both HIV positive and HIV negative MSM remains important, including routine HCV antibody screening at STI clinics and cheaper viral load tests to distinguish between acute and chronic infection.
AT Urbanus, T van de Laar, R Geskus, et al. Prevalence, incidence and determinants of HCV infections among HIV-positive MSM attending a STI clinic, 1995-2010. XIX International AIDS Conference (AIDS 2012). Washington, DC, July 22-27, 2012. Abstract TUAC0503.