MSM starting preexposure prophylaxis are at risk of hepatitis C virus infection.

Objectives And Design: Hepatitis C virus (HCV) has been recognized as an emerging sexually transmitted infection (STI) among HIV-positive MSM. However, HIV-negative MSM at high risk for HIV might also be at increased risk for HCV. We studied the HCV prevalence in HIV-negative MSM who start preexposure prophylaxis (PrEP) in Amsterdam. Phylogenetic analysis was used to compare HCV strains obtained from HIV-negative and HIV-positive MSM.

Methods: At enrolment in the Amsterdam PrEP demonstration project, HIV-negative MSM were tested for the presence of HCV antibodies and HCV RNA. If positive for HCV RNA, an HCV NS5B gene fragment (709 bp) was sequenced and compared with HCV isolates from HIV-positive MSM (n = 223) and risk groups other than MSM (n = 153), using phylogenetic analysis.

Results: Of 375 HIV-negative MSM enrolled in Amsterdam PrEP, 18 (4.8%, 95% confidence interval 2.9-7.5%) of participants were anti-HCV and/or HCV RNA positive at enrolment; 15 of 18 (83%) had detectable HCV RNA. HCV genotyping showed genotype 1a (73%), 4d (20%), and 2b (7%). All HCV-positive MSM starting PrEP were part of MSM-specific HCV clusters containing MSM with and without HIV.

Conclusion: HCV prevalence among HIV-negative MSM who started PrEP was higher than previously reported. All HIV-negative HCV-positive MSM were infected with HCV strains already circulating among HIV-positive MSM. The increasing overlap between sexual networks of HIV-positive and HIV-negative MSM might result in an expanding HCV-epidemic irrespective of HIV-status. Hence, routine HCV testing should be offered to MSM at high risk for HIV, especially for those enrolling in PrEP programs.