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Almost half of MSM with HIV/HCV co-infection have HCV in their rectal fluid
Michael Carter, 2016-12-08 07:50:00
Almost half of
HIV-positive men who have sex with men (MSM) who have co-infection with hepatitis C virus (HCV) have detectable HCV in their rectal fluid, US investigators report in the
online edition of Clinical Infectious
Diseases. The presence and level of HCV in rectal fluid was strongly
associated with the level of HCV in blood.
provides the first direct evidence that HCV is shed into the rectum of
HIV-infected men,” comment the authors. “We found HCV at substantial levels in
the rectal fluid of almost half the HIV-infected men we studied.”
believe their findings support the hypothesis that rectal bleeding is not
needed for the sexual transmission of HCV infection between MSM. They call for
the development of health promotion interventions that reflect their findings.
The first cases of
sexual transmission of HCV involving HIV-positive MSM were reported in the
early 2000s and there are now well-established epidemics of sexually
transmitted HCV involving HIV-positive MSM in a number of European and US
cities. Despite this, there is still considerable uncertainty about the body
fluids involved in transmission and the precise sexual practices that carry the
highest risk of infection with the virus.
New York City therefore designed an observational study involving 43
HIV-positive MSM with HCV co-infection. HCV viral load was quantified in paired
samples of rectal mucus and blood. Sixty per cent of participants were white and
the median age was 43 years. All were taking antiretroviral therapy, but
because of poor adherence, only 49% had viral suppression.
patients had high-resolution anoscopy at the time rectal fluid was sampled.
None of these individuals had evidence of rectal trauma or bleeding. However, blood
was detected on the rectal swab from a man who did not initially undergo
anoscopy. Subsequent anoscopy revealed the presence of proctitis.
HCV in rectal
fluid was detected in 47% of men. The median HCV viral load in rectal fluid was
2.9 log10 IU/ml. Blood viral load was significantly higher among men
with HCV in their rectal fluid compared to those in whom it was not detected
(6.4 log10 IU/ml vs. 4.0 log10 IU/ml, respectively, p
The presence of
HCV in rectal fluid was strongly associated with HCV viral load in blood above
5 log10 IU/ml (p = 0.001) and even more strongly with blood HCV
viral load above 6 log10 IU/ml (p < 0.001). Moreover, 85% of
those with a blood HCV viral load above 5 log10 IU/ml and 90% of
individuals with a blood HCV viral load above 6 log10 IU/ml had HCV
in their rectal fluid.
There was a
significant positive correlation between the level of HCV in rectal fluid and
HCV viral load in blood. High-level rectal shedding of HCV – 4 to 5 log10
IU/ml – was detected in a quarter of patients with a blood viral load above 6
log10 IU/ml. The man with the highest rectal HCV viral load (5.2 log10
IU/ml) was the patient with visible blood on his rectal swab and proctitis.
“These results support the accumulating
epidemiological evidence that rectal bleeding is not required for transmission
of HCV infection among HIV-infected MSM, and may be the explanation for the
epidemiological associations found in some studies between group sex or
fisting,” write the authors. “We suggest that for clinical and public health
purposes, finding HCV RNA in rectal fluid should be taken as evidence of
infectiousness until proven otherwise.”
conclude that, “semen and rectal fluid, rather than frank blood from the
rectum, are likely the fluids that mediate most HCV infections in this
epidemic.” They call for public health campaigns to educate MSM about these
routes of HCV transmission.