Heterosexual co-transmission of hepatitis C virus (HCV) and human immunodeficiency virus (HIV).

OBJECTIVES: To determine the prevalence of antibodies to hepatitis C virus (HCV) in female sexual partners of multitransfused men with hemophilia and to compare the frequency of transmission of HCV and human immunodeficiency virus (HIV). STUDY DESIGN: Cross-sectional measurement of HCV and HIV antibodies. SETTING: Ten hemophilia treatment centers. PATIENTS: A total of 234 female sexual partners of 231 multitransfused men with hemophilia. MEASUREMENTS AND MAIN RESULTS: The prevalence of antibodies to HCV (anti-HCV) among female sexual partners of HCV-positive men was 5 of 194 (2.6%). Anti-HIV prevalence among female sexual partners of HIV-positive men was 25 of 196 (12.8%). Five (3%) of the 164 female sexual partners of HIV-positive/HCV-positive men were infected with HCV compared with none of the 30 female sexual partners of HIV-negative/HCV-positive men. Twenty-one (13%) of the 164 female sexual partners of HIV-positive/HCV-positive men were infected with HIV compared with 4 (13%) of 32 female sexual partners of HIV-positive/HCV-indeterminate men. The co-infected men were five times more likely to transmit both viruses than would be expected by chance (P = 0.01). When a single virus was transmitted to a female sexual partner, it was more often HIV than HCV (18 of 164 compared with 2 of 164, P = 0.001; odds ratio, 8.5; 95% Cl, 2.2 to 33.1). CONCLUSIONS: The higher prevalence of HCV in female sexual partners of men with hemophilia than in blood donor and other low-risk groups suggests that there is a low level of sexual transmission. Male to female sexual transmission of HCV is less efficient than that of HIV. The frequency of HCV transmission to sexual partners is five times higher when HIV is also transmitted, suggesting that HIV may be a cofactor for the sexual transmission of HCV.