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Sexual Transmission of Hepatitis C Virus in Heterosexual Monogomous Couples – The HCV Partners Study
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Reported by Jules Levin
Norah A Terrault, University of California San Francisco, San Francisco, CA; Michael Busch, Edward Murphy, Blood Centers of the Pacific, San Francisco, CA; Maria Tong, Jenya Dvorkin, University of California San Francisco, San Francisco, CA; Miriam J Alter, Centers for Disease Control and Prevention, Atlanta, GA
Prior studies on sexual transmission of HCV in heterosexual couples have been limited by small sample size, failure to exclude non-sexual routes of HCV transmission, and failure to characterize anti-HCV concordant couples virologically.
The aim of this study is to determine the potential for sexual transmission of HCV among monogamous heterosexual couples by identifying the factors (sexual and non-sexual) associated with anti-HCV positivity among partners, and the relatedness of virus strains among concordant couples. (edit note: published studies show sexual transmission risk increases when there are multiple sex partners, anal sex, sex during menstruation, STDs or HIV are present, open sores, herpes).
Anti-HCV positive persons (without HIV and HBV coinfection) with a monogamous heterosexual partner for at least 3 years and no history of injection drug use (IDU) in both partners were eligible. Partners were tested for anti-HCV (EIA-2, RIBA-3), qualitative HCV RNA and HCV genotype/serotype (=type) as appropriate. HCV type concordant couples underwent sequencing and phylogenetic analysis (pending). Detailed information on HCV risk factors and sexual practices were obtained by interviewing the partners separately.
Of 2077 couples screened, 672 were eligible, 552 enrolled and 500 completed the study. The most common reasons for study ineligibility were lack of sexual partner (40%), prior organ transplant (15%), HIV or HBV coinfection (10%), partnership <3 years or non-monogamous (8%), and IDU in both partners (8%). The median age of partners was 49 yrs (range 27-79) and 75% were Caucasian. The median duration of sexual contact was 16 yrs (range 3-52); the median number of sexual contacts per month per couple ranged from 0.3 to 24.4. The proportions of couples engaging in vaginal, anal, oral active and oral receptive sex were 98.3%, 12.5%, 77%, and 76%, respectively. Use of condoms was reported by 80%, but only 17% reported frequent or regular condom use. A total of 20 (4%) partners tested positive for anti-HCV (EIA and RIBA) and 12 had detectable HCV RNA. The type and frequency of sexual contacts and frequency of sharing personal items (e.g. razors) did not differ between anti-HCV positive and negative partners (all p>0.05). Anti-HCV positive partners had higher rates of IDU (45% vs 1%, P<0.001), tattoos (45% vs 15%, P=0.007), blood brother rituals (37% vs 12%, p=0.0015), bloody needlestick injury (60% vs 14% (p=0.005), and total number of sex partners (p=0.005).
In multivariate analysis, only IDU, tattoos and needlestick injury were independently associated with anti-HCV positivity in the partners. Genotypes/serotypes were discordant in 6 couples and concordant in 9 couples tested to date. Sexual contact rates of type concordant couples tended to be higher than type discordant couples (median 1 vs 0.25 contact per mos, p=0.07) but with no differences in types of sexual practices. The frequency of percutaneous risk factors for HCV in both partners tended to be higher in discordant than concordant couples (3/5 vs 1/9, p=0.09).
The prevalence of anti-HCV among sexual partners of persons with HCV was 4% (95% CI: 2.3%-5.7%) but 40% of partners had discordant types indicating lack of sexual transmission. The majority of type concordant couples lacked percutaneous risk factors for HCV, suggesting sex may be the route of transmission but phylogenetic analysis of viral strains will ultimately determine whether sexual transmission occurred.
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