Increase in HCV incidence among men who have sex with men in Amsterdam most likely caused by sexual transmission

We retrospectively screened 1836 men who have sex with men ( MSM) participating in the Amsterdam Cohort Studies ( 1984 - 2003) for hepatitis C virus ( HCV) antibodies. HCV incidence was 0.18/ 100 person- years ( PY) in human immunodeficiency virus ( HIV) - positive MSM ( 8/ 4408 PY [ 95% confidence interval {CI}, 0.08 - 0.36]) but was 0/ 100 PY in MSM without HIV ( 0/ 7807 PY [ 95% CI, 0.00 - 0.05]). After 2000, HCV incidence among HIV- positive men increased 10- fold to 0.87/ 100 PY ( 5/ 572 PY [ 95% CI, 0.28 - 2.03]). Additional hospital cases (n=34) showed that MSM in Amsterdam who acquired HCV infection after 2000 reported high rates of ulcerative sexually transmitted infections ( 59%) and rough sexual techniques ( 56%), denied injection drug use, and were infected mainly with the difficult- to- treat HCV genotypes 1 ( 56%) and 4 ( 36%). Phylogenetic analysis showed 3 monophyletic clusters of MSM- specific HCV strains. The emergence of an MSM- specific transmission network suggests that HIV- positive MSM with high- risk sexual behaviors are at risk for sexually acquired HCV. Targeted prevention and routine HCV screening among HIV- positive MSM is needed to deter the spread of HCV.