Sexual Transmission of Hepatitis C in MSM May Not Be Confined to Those with HIV Infection

To the Editor—We concur with van de Laar et al. [1] that sexual transmission of hepatitis C virus (HCV) among human immunodeficiency virus (HIV)–infected men who have sex with men (MSM) appears to be increasing. Similar outbreaks have been reported in other parts of the world [2–4]. These reports have demonstrated an association with other sexually transmitted infections. However, it is unclear whether this increasing incidence is occurring exclusively among HIV-infected MSM or whether this apparent exclusivity simply reflects a lack of data from HIV-uninfected MSM. Regular HCV screening is not currently recommended for MSM without HIV infection, and unlike HIV-infected MSM, these individuals are unlikely to have had the opportunity for HCV infection to be suspected on the basis of results of routine liver function tests [5]. The aim of our analysis was to describe the incidence of HCV infection among MSM who attended the only public sexual health clinic in Brighton, United Kingdom, between 2000 and 2006 We have been performing HCV screening regularly since 2000 among all MSM attending our clinic, regardless of their HIV status. In this analysis, we included all MSM with ⩾2 clinic visits during the study period who had a negative result of their first HCV antibody test. The follow-up interval began on the date of their first HCV antibody test and ended on the date of their first positive HCV test result, 6 months after their most recent clinic visit, or on 31 December 2006, whichever occurred first. Poisson regression analysis was used to assess the impacts of HIV status at the time of the initial HCV test and calendar year on the rate of new HCV infections. We excluded MSM with a history of injection drug use (IDU) A total of 6124 MSM were seen at least twice in our clinic over the study period, of whom 3536 met the eligibility criteria. Forty-four patients were excluded because the result of their first HCV antibody test was positive, and 2544 were excluded because they had not been tested for HCV. Over the study period, 25 MSM had incident HCV infection, for an incidence rate of 3.7 cases per 1000 person-years (95% confidence interval [CI], 2.3–5.2). Nine diagnoses of incident HCV infection occurred among individuals without HIV infection (rate, 5 cases per 3335 person-years, or 1.5 cases per 1000 person-years [95% CI, 0.5–3.5]) or with an unknown HIV status (rate, 4 cases per 1971 person-years, or 2.0 cases per 1000 person-years [95% CI, 0.6–5.2]) at the time of their first HCV test, whereas 16 diagnoses of incident HCV infection per 1361 person-years (11.8 cases per 1000 person-years [95% CI, 6.7–19.1]) occurred among individuals known to have HIV infection. The number of new HCV diagnoses increased annually during 2003–2006, with incidence rates of 1.6 cases per 1000 person-years (95% CI, 0.2–5.7) in 2003, 2.4 cases per 1000 person-years (95% CI, 0.7–6.1) in 2004, 3.5 cases per 1000 person-years (95% CI, 1.3–7.6) in 2005, and 9.0 cases per 1000 person-years (95% CI, 4.8–15.4) in 2006. During the study period, incidence rates increased annually among MSM known to have HIV infection at the time of their first HCV test (5.9, 11.1, 11.4, and 17.5 cases per 1000 person-years, respectively, during 2000–2003, 2004, 2005, and 2006) and among those whose HIV status was unknown or negative (0, 0.7, 1.5, and 5.8 cases per 1000 person-years, respectively, during 2000–2003, 2004, 2005, and 2006). Multivariable Poisson regression analysis confirmed that HIV status at the time of the first HCV test and calendar year were independently associated with incident HCV infection. Rate ratios were 7.01 (95% CI, 2.55–19.26) for MSM with known HIV infection and 1.49 (95% CI, 0.40–5.58) for MSM with an unknown HIV status, compared with MSM without HIV infection (global P=.0001). Rate ratios were 2.37 (95% CI, 0.43–12.97) for 2004, 3.12 (95% CI, 0.63–15.49) for 2005, and 6.79 (95% CI, 1.52–30.24) for 2006, compared with 2000–2003 (global P=.02) The high rate of HCV transmission among HIV-infected MSM who were non-IDUs concurs with the findings reported by van de Laar et al. [1] and others. However, to our knowledge, this is the first report of significant sexual transmission of HCV to MSM whose HIV status was either negative or unknown at the time of their first HCV test. Although some of these MSM subsequently received a diagnosis of HIV infection at the time of their first positive HCV test result, HIV infection had not been diagnosed when they were screened for HCV It remains unclear why HIV-infected MSM appear to have a greater risk than HIV-uninfected men for acquiring HCV. MSM with HIV infection have higher seminal HCV loads than HIV-uninfected MSM and are more likely to transmit HCV [6]. Furthermore, studies have demonstrated that many MSM “serosort” (i.e., they have unprotected anal sex only with partners whose HIV-infection status is the same as their own), which may contribute to the imbalanced incidence rate of HCV infection between HIV-infected and HIV-uninfected MSM [7] Given the available evidence, we propose that all HIV-infected MSM should be screened for HCV on an annual basis but that all MSM, regardless of HIV status, should be screened for HCV in settings where outbreaks of HCV infection are known to have occurred and where MSM are known to participate in high-risk behaviors [2]. It is also clear that incident HCV infection reflects ongoing HIV risk and that all individuals, particularly those with incident HCV infection, should be targeted by behavioral interventions to reduce ongoing transmission