BACKGROUND: Hepatitis C Virus (HCV) is a blood-borne pathogen that is rarely transmitted sexually among monogamous heterosexual couples. However, risky behaviors among men who have sex with men (MSM) (e.g. fisting, use of sex toys, anal douching), particularly in the presence of HIV infection and/or ulcerative STDs, have been associated with increased risk of sexual transmission of HCV. We report on a cluster investigation of sexually transmitted HCV in the MSM population in Southeast Michigan; a rare occurrence in the United States.
METHODS: In February 2016, an astute clinician notified the Michigan Department of Health and Human Services (MDHHS) about an increase in HCV diagnoses in their HIV-infected MSM population. MDHHS began an investigation to determine the scope of the HCV infections. Additional cases were identified using retrospective data matching and prospective surveillance and laboratory monitoring. Demographic, clinical, and risk factor information were captured to inform the epidemiological investigation. Additionally, Hepatitis C testing was established at the Detroit STD Clinic for any individuals who identify as MSM in order to detect additional cases.
RESULTS: As of December 1, 2016 there were 24 cases in the cluster, with several dozen contacts still under investigation. All nineteen of the cases were male and 23 were African American with one Hispanic. All twenty-four were infected with HIV, 24 reported never injecting drugs and 24 reported having sex with men. A history of having an STD was common - syphilis (17), gonorrhea (14), chlamydia (14), and lymphogranuloma venereum (5). Many HCV infections were acute or new seroconversions suggesting recent infection and of 12 isolates that underwent genotyping, all were HCV genotype 1a.
CONCLUSIONS: We describe the recent transmission of HCV in the MSM population in southeastern Michigan. Epidemiological information ascertained from patient investigation suggests that these infections were transmitted sexually and not by intravenous drug use. Clusters of this magnitude have rarely been described in the U.S. Sexual transmission of HCV may be an underappreciated mode of acquisition in the MSM population. In addition, strong relationships between clinicians, laboratories, local and state public health departments, and hepatitis, STD, and HIV surveillance and prevention groups were necessary to detect and respond to such a cluster. Additional molecular characterization of the HCV specimens will help further determine HCV transmission patterns in this community.