Background:  To assess incidence, genotype (GT) distribution, and prognosis of sexually transmitted acute hepatitis C infection since 2001, in a cohort of predominantly MSM.

Methods:  Cases of acute hepatitis C were identified from a cohort of 4421 HIV-infected subjects since January 2001. Rate ratios were determined and compared, and GT distribution and clinical course with or without pegIFN/RBV treatment was analyzed.

Results:  In the study, 46 cases were identified (all MSM). Thirty-two subjects received HAART and 14 were untreated for HIV. Incidence rates (95%CI) per 1000 PYFU increased over time: 2001 to 2002: 0.15 (-0.14 to 0.43); 2003 to 2004: 1.31 (0.54 to 2.08); 2005 to 2006: 2.08 (1.03 to 3.13); 2007 to 2008: 2.48 (1.36 to 3.59). 20 (43%) had HCV GT 1, 1 (2%) GT 2, 9 (20%) GT 3, and 16 (35%) GT 4. Thirty-four subjects received peg-IFN/RBV. SVR was achieved in 20 (65% of the 31 subjects with follow-up after treatment), relapse occurred in 3 (10%), and primary non-response was observed in 8 (26%). Currently, 3 subjects are on treatment. Ten patients (22%/46) cleared HCV spontaneously, and 2 (4%) remain untreated with persistent infection. Re-infection occurred in 5 individuals (17%) of those who cleared acute hepatitis C infection (3 with different genotypes, 1 with the same, 1 with pending GT). After primary infection with GT3, one patient developed severe hepatitis upon second re-infection with GT1; this patient cleared HCV all 3 times without therapy.

Conclusions:  We observed an increase in acute, sexually transmitted HCV infections since 2001. The high prevalence of GT 4 compared with other case series argues for regional differences in the transmission of HCV strains. Overall, 65% of all infected subjects achieved SVR either spontaneously or by treatment. Re-infection appears to occur frequently, emphasizing the need for further prevention efforts. Future studies should investigate the contribution of acute acute hepatitis C infection to acute hepatitis C infection transmission and possible epidemiological links between subjects with the same genotype.