- Category: Gay & Bisexual Men/MSM
- Published on Friday, 09 November 2012 00:00
- Written by Liz Highleyman
Sexually transmitted hepatitis C virus (HCV) infection has increased dramatically over the past 13 years among gay and bisexual men in the Swiss HIV Cohort Study, even as it remained stable among heterosexuals and decreased among injection drug users, investigators reported in the November 2012 issue of Clinical Infectious Diseases.
Around the year 2000 clinicians began reporting outbreaks of apparently sexually transmitted acute HCV infection among men who have sex with men (MSM), first in cities in the U.K., then in continental Europe, followed by Australia and the U.S. HCV acquisition has been linked to various sexual activities, other sexually transmitted infections, use of non-injected recreational drugs, and sex in group settings, but the exact risk factors have varied from study to study.
HIV/HCV coinfected people tend to experience faster liver disease progression and respond less well to hepatitis C treatment; some research indicates that people who are already HIV positive when they acquire HCV may experience very rapid fibrosis progression, though this remains controversial.
Gilles Wandeler from Bern University Hospital and fellow investigators with the Swiss HIV Cohort Study looked at trends in hepatitis C incidence among different HIV transmission groups in the cohort.
HCV incidence was assessed from 1998 -- when they study started doing routine serial HCV screening -- through 2011. All initially HCV seronegative study participants with at least 1 follow-up test were included: 4629 MSM, 4530 people who acquired HIV through heterosexual contact, and 2678 current or past injection drug users (IDUs).
- 147 MSM (3.2%), 513 heterosexual men and women (11.3%), and 2468 IDUs (92.2%) were HCV positive at baseline, leaving 3333 MSM, 3078 heterosexuals, and 123 IDUs in the HCV incidence analysis.
- Overall, IDUs continued to have the highest HCV seroconversion rate:
o IDUs: 41 people per 733 person years of follow-up, or 33%;
o MSM: 101 people per 23,707 person-years, or 3%;
o Heterosexuals: 25 people per 20,752 person-years, or 1%.
- MSM, however, saw the largest incidence rate increase:
o MSM: increase from 0.23 per 100 person-years in 1998 to 4.09 in 2011 (51 new cases -- half the total -- occurred during the last 3 years).
o IDU: decrease from 13.89 per 100 person-years in 1998 to 2.24 in 2011 (3 cases during the last 3 years);
o Heterosexual: stable at < 0.5 per 100 person-years (2 cases in 2011).
- Of the 63 new infections among MSM with available genotyping results, a majority were HCV genotype 1 (67%), followed by genotypes 4 (19%), 3 (13%), and 2 (2%).
- After adjusting for other factors, the only significant predictors of HCV seroconversion among MSM were inconsistent condom use (adjusted hazard ratio [HR] 2.09) and history of syphilis (adjusted HR 2.11), both approximately doubling the risk.
"In the Swiss HIV Cohort Study, HCV infection incidence decreased in [IDUs], remained stable in [heterosexuals], and increased 18-fold in MSM in the last 13 years," the study authors summarized. "These observations underscore the need for improved HCV surveillance and prevention among HIV-infected MSM."
In their discussion, they attributed the decreased HCV incidence among IDUs to "the considerable success of preventive interventions such as methadone substitution and needle exchange programs," as well as Switzerland's long-term heroin prescription program.
The researchers explained that most demographic and behavioral characteristics were similar for gay/bisexual men who acquired HCV and those who did not, making it difficult to identify the cause of the increased incidence beyond not using condoms for anal sex. Non-injection drug use, use of antiretroviral therapy (ART), and immunological status were not significantly associated with HCV infection; almost all men who seroconverted were on ART (93%) and had CD4 T-cell counts >200 cells/mm3.
However, they noted that there had been a significant increase in syphilis among MSM in the cohort, paralleling the HCV epidemic. "[I]t is...conceivable that the mucosal disruption caused by syphilitic ulcers facilitates HCV infections," they suggested. They also pointed out that condom use has declined in recent years among MSM in the cohort with suppressed HIV viral load.
"It is crucial that HIV-infected MSM are counseled with regard to the risks of sexual activities that involve traumatic mucosal sex, and that condoms are used consistently during high-risk sexual activity," they concluded. "The example of IDUs demonstrates that it is possible to reduce the incidence of HCV infections through improved screening and preventive interventions."
G Wandeler, T Gsponer, A Bregenzer, A Rauch, et al. HepatitisC Virus Infections in the Swiss HIV Cohort Study: A Rapidly Evolving Epidemic. Clinical Infectious Diseases55(10):1408-1416. November 2012.