Route of HCV transmission in HIV-positive gay men is unlikely to be from semen
Simon Collins, HIV i-Base
The mechanism for high rates of hepatitis C (HCV) transmission in HIV-positive gay men is unknown with little data on whether HCV levels in semen had a similar risk factor to HIV viral load, especially during acute infection.
Joanna Turner and colleagues presented a new study to inform this field. 
Paired blood and semen samples were collected from 5 acute and 9 chronic HCV cases in HIV-positive men. At baseline 0/5 acute and 2/9 chronic cases had detectable HCV RNA in semen. Of all samples tested 2/10 (20%) of acute cases and 4/23 (17%) of chronic cases (p=NS) had detectable HCV RNA in semen.
However, when detected, HCV RNA viral loads were low: <30 IU/mL (acute cases) and <230 IU/mL (chronic cases) and did not correlate with plasma HCV viral load
Taken together, this lead the researcher to suggests that the quantity of seminal HCV virus is not a significant factor in determining the rate of HCV transmission, even during acute infection. Recruitment to the study is ongoing.
HCV levels in semen have been previously reported.  Results from the larger study will be important to understand whether infection from semen is likely to occur at these low levels.
1. Turner J et al. Hepatitis C viral load in semen of HIV-positive men during acute and chronic hepatitis C infection. 2nd Joint Conference of BHIVA with BASHH, 2023 April 2010, Manchester. Oral abstract O5.
2. See this earlier report in HTB from 2003.