|
Unsafe Sexual
Behavior among HIV Positive Men Who Have Sex with Men Is Associated
with New Acquisition of HCV Infection
 The
primary transmission
routes of HCV infection are injection
drug use (IDU) with needle sharing,
occupational exposure in health care workers,
contaminated blood products, transplants, use of medical and paramedical devices, and vertical
transmission. Whether
and how frequently hepatitis C virus is transmitted through
sexual intercourse is a controversial and at times contentious
issue.
Of
note, the published literature gives significantly more weight
to the notion that sexual transmission of HCV does indeed
occur among gay men through unprotected anal intercourse,
while it tends to minimize the risk for transmission of HCV
through unprotected vaginal intercourse among heterosexuals.
Data
on the issue of HCV transmission through unsafe sex among
HIV positive men who have sex with men in the Swiss HIV Cohort
Study is reported in the August 1, 2005 issue of Clinical
Infectious Diseases [1]. Following is a summary of these
data and selected excerpts from the published study:
Data
on the incidence of hepatitis C virus
(HCV) infection among HIV infected persons
are sparse.
Researchers
of the Swiss HIV Study Cohort (SHCS) assessed the prevalence
and incidence of HCV infection in the Swiss
HIV Cohort Study between 1988 and 2004. They investigated
the association of HCV seroconversion with mode of HIV acquisition, sex, injection
drug use (IDU),
and consistency of condom use. Data on condom
use or unsafe sexual behavior were prospectively collected between 2000 and 2004.
Results
· The
overall seroprevalence of HCV infection was 33% among a total of 7899 eligible participants
and 90% among persons reporting IDU.
· 04 HCV seroconversions among 3327 participants
were seen during a total follow-up time of 16,305 person-years, corresponding to an incidence
of 0.64 cases per 100 person-years.
· The incidence among participants with a history
of IDU was 7.4 cases per 100 person-years,
compared with 0.23 cases per 100 person-years
in patients without such a history (P < .001).
· In
men who had sex with men
(MSM) without a history of IDU who reported
unsafe sex, the incidence
was 0.7 cases per 100 person-years, compared with 0.2 cases per 100 person-years in those not reporting unsafe sex (P = .02).
·
The hazard of acquiring HCV infection was elevated
among younger participants who were MSM.
Commentary
These
results reflect continuing HCV infection in a nationwide cohort of adult persons with HIV infection
in Switzerland. HCV incidence is highest
in persons with a history of IDU. HCV infections
occur also in persons without reported
IDU, although at an incidence rate 30 times
lower. Intriguingly, HCV infection is associated
with inconsistent condom use in MSM
in this large cohort [emphasis added—Ed]
HCV infections in
serodiscordant couples are rarely observed, at
least not in heterosexual couples. Many experts
therefore conclude that sexual transmission of
HCV is of little importance. Nevertheless,
concurrent genital ulcers caused by genital
herpes simplex
or syphilis might facilitate
transmission of HCV if condoms are not consistently used.
In some studies, HCV
prevalence was associated with increased numbers of sexual partners and intercourses,
especially among MSM ; others,
however, could not find such an association.
These contradictory results can be explained
by differences in study design, because most studies were cross-sectional analyses.
Although the findings were
based on a small number of seroconversions,
the researchers found a statistically significant
association between reporting unsafe sex and HCV infection among MSM in recent years.
They conclude that inconsistent condom use
bears a small but significant risk for HCV
infection in unprotected male homosexual contacts.
Of note, there are recent reports of small epidemics of HCV infection
in the gay community [2]. The researchers observed
a significant trend towards an increased risk
of HCV seroconversion in younger MSM. If HCV
is sexually transmissible, this finding is in concordance with a recent report about a
lower adherence to safer sex in younger
participants in the SHCS and with the
higher proportion of younger MSM participants in this analysis reporting unsafe sex.
The association between
serological test results positive for syphilis
and the incidence of HCV infection in
the MSM population further points towards possible sexual
transmission of HCV infection.
With regard to heterosexual
relationships without consistent condom use, these
study data do not show a statistically
significant increased risk of HCV infection; however, the point estimate of the hazard ratio for unsafe sex was 3.0. This clearly does not allow one to exclude such a risk.
This is the first study
to report an association of unsafe sex with
an increased incidence of HCV infection in HIV-infected MSM that was determined on the
basis of prospective longitudinal cohort data
that included regular HCV testing and reports about condom use and IDU.
In conclusion, the authors write, “Data of the large,
prospective SHCS indicate that unsafe sexual behavior among MSM is associated with new acquisition
of HCV infection and that HCV seroconversion
continues to occur among IDU, even though
needle exchange programs are available in Switzerland.”
“Thus,
physicians caring for HIV-infected persons need
to emphasize the prevention of HCV infection
among their patients with continuing IDU and
motivate MSM to practice safe sex because of the additional risk of transmitting and
acquiring HCV infection.”
Division of Infectious Diseases, University Hospital Berne, Data Center Swiss HIV Cohort Study, Lausanne, Division of Infectious Diseases, University Hospital Zurich, Division of Infectious Diseases, University Hospital Geneva, Division of Infectious Diseases, University Hospital Lausanne, Basel Institute for Clinical Epidemiology, University Hospital Basel, Division of Infectious Diseases, Kantonsspital St. Gallen, and Division of Infectious Diseases, Ospedale Civico Lugano, Switzerland.
07/13/05
References
1.
A Rauch and others (the Swiss HIV Cohort Study). Unsafe Sex and Increased Incidence of Hepatitis C Virus Infection among HIV-Infected Men Who Have Sex with Men: The Swiss HIV Cohort Study. Clinical
Infectious Diseases 41(2): 395-402. August 1, 2005.
2.
R Browne and others. Increased numbers of acute
hepatitis C infections in HIV-positive homosexual men: is
sexual transmission feeding the increase? Sexually Transmitted
Infections 80: 326-327. 2004.
|
