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Incidence of hepatitis C virus
infections has increased eighteen fold in HIV-positive gay men in Switzerland
since 1998, investigators report in the online edition of Clinical Infectious
Diseases. Half of all infections in gay men occurred between 2008 and 2011. In
contrast, incidence of hepatitis C fell in HIV-positive injecting drug users
and remained stable in HIV-positive heterosexuals.
“We found that the yearly incidence
rate had decreased in IDU [injecting drug users], remained stable in HET
[heterosexuals] and dramatically increased in MSM [men who have sex with men],”
write the authors. “In MSM, a history of inconsistent condom use and a past
episode of syphilis were significantly associated with HCV [hepatitis C virus]
seroconversion.”
Liver disease caused by hepatitis C
is now a major cause of serious illness and death in people with HIV. For many
years, hepatitis C co-infection almost exclusively occurred in injecting drug
users and recipients of blood products.
However, over the past decade there
have been outbreaks of sexually transmitted hepatitis C in HIV-positive gay
men. These infections have been linked to unprotected sex, traumatic mucosal
activities such as fisting, and have also occurred within sexual networks. Such
an outbreak has been observed among HIV-positive gay men in Zurich.
Investigators from the Swiss HIV
Cohort Study wished to establish a better understanding of the wider dynamics
of hepatitis C epidemiology in the HIV-positive people in their care.
They therefore examined incidence of
the infection in three risk groups: gay men, injecting drug users and
heterosexuals.
Incidence rates were monitored over
a 13-year period, between 1998 and 2011.
The investigators also examined
whether any risk factors for incident hepatitis C infections in gay men could
be identified.
A total of 12,000 people were
included in the study. Prevalence of hepatitis C co-infection at baseline was
3% for gay men, 92% for injecting drug users and 11% for heterosexuals.
A total of 3333 gay men were then
included in the prospective analysis, as were 123 injecting drug users and 3078
heterosexuals.
During follow-up, 3% of gay men
became infected with hepatitis C, as did a third of injecting drug users and 1%
of heterosexuals.
The dynamics of the hepatitis C
epidemic differed between risk groups.
In gay men, incidence increased from
0.23 per 100 person years in 1998 to 4.09 per 100 person years in 2011. In all,
51 of the 101 infections observed over the entire study period occurred between
2008 and 2011.
“Clinicians and patients should be
aware of the risk of acute HCV infections in MSM,” write the researchers.
“Intensified prevention and counseling should be performed.”
In contrast, incidence among
injecting drug users declined from 13.89 per 100 person years in 1998 to 2.24
per 100 person years in 2011. Only three infections in this group were recorded
between 2008 and 2011.
“Switzerland’s long-term heroin
prescription program likely contributed to the decreasing incidence of HCV
seroconversion in this population,” comment the investigators.
Incidence in heterosexuals was low
at approximately 0.5 per 100 person years across the study period. The
investigators speculate that many of these infections may in fact be due to
either undisclosed injecting drug use or due to sex between men. “Recent phylogenetic
studies within the Swiss HIV Cohort Study…revealed that approximately 11% of
HIV-pol sequences from heterosexuals were linked to transmission clusters in
MSM,” note the authors.
Risky sexual behavior appeared to be
the driving the epidemic in gay men.
The investigators found that
inconsistent condom use doubled the risk of hepatitis C seroconversion (aHR =
2.09; 95% CI, 1.33-3.29) in this group. Incident hepatitis C infection was also
associated with a previous syphilis diagnosis (aHR = 2.01; 95% CI, 1.39-3.20).
Two-thirds of hepatitis C infections
among gay men involved hepatitis C genotype-1 and 19% genotype-4. These are the
harder to treat of the hepatitis C genotypes.
“It is crucial that HIV-infected MSM
are counseled with regard to the risk of sexual activities that involve
traumatic mucosal sex, and that condoms are consistently used in sexual risk
situations,” conclude the investigators. “The example of IDUs demonstrates that
it is possible to reduce the incidence of HCV infections through improved
screening and preventative interventions.”
The Friends of AIDS Foundation is
dedicated to enhancing the quality of life for HIV positive individuals and
empowering people to make healthy choices to prevent the spread of the HIV
virus. To learn more about The Friends of AIDS Foundation, please visit: http://www.friendsofaids.org.
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