Such nonpercutaneous routes of hepatitis C virus (HCV) transmission of hepatitis C. Whereas direct, percutaneous inoculation, eg, via transfusion or self-injection of addictive transmission as sexual and perinatal spread are relatively inefficient. Several observations have been cited to support a role drugs, is very efficient in transmitting HCV infection, less direct, so-called nonpercutaneous routes of infection are inef-for sexual transmission of hepatitis C. Approximately 10% of persons with reported cases of acute hepatitis C in the United ficient in the spread of hepatitis C. States report a history of potential sexual exposure. Anecdotal SEXUAL TRANSMISSION
cases of sexual transmission have been reported, and HCV nucleotide sequence homology has been observed in viral
Among patients with reported cases of acute hepatitis C isolates from sexual partners. Similarly, the prevalence of in the United States, a history of recent (within 6 months) HCV infection is increased in groups with a high risk of sexual contact with a person at risk for HCV infection, that exposure to sexually transmitted viral infections. Other obseris, potential sexual exposure, can be elicited in approximately vations, however, weigh against sexual transmission of HCV 10% of cases. 1,2 In addition, certain subpopulations with recinfection. Sexual transmission is negligible in sex-partner ognized frequent, multipartner sexual activity, such as prostudies; alternative risk factors account for many cases of fessional sex workers (prostitutes), promiscuous homosexual apparent sexual transmission between sexual partners; the men, and persons of both sexes attending clinics for sexually prevalence of HCV infection in high-risk groups is much lower transmitted diseases, have a higher frequency of serologic than that of other sexually transmitted infections; and the markers of HCV infection than the general population. The risk of apparently sexually transmitted HCV infection does question arises, however, whether high frequencies of HCV not always correlate with intensity and duration of sexual infection in such high-risk groups resulted from sexual or exposure. The United States Public Health Service has estinonsexual transmission. In an analysis of reports published mated that the risk of sexual transmission is approximately before 1995, prevalences of antibody to HCV (anti-HCV) in 5%, well below the risk of sexual transmission of hepatitis B sexual partners of persons with chronic hepatitis C ranged or human immunodeficiency virus (HIV). Similarly, perinatal form 0% to 27%. 3 For sexual partners of persons with high-HCV infection, though documented to occur, is unusual, exrisk behavior (eg, sexual promiscuity, injection drug use), cept in babies born to mothers with very high levels of HCV anti-HCV prevalences were higher (11% to 27%) than preva-RNA, including mothers with concomitant HIV infection. lences in sexual contacts of persons without high-risk behav-Weighing many, often conflicting reports, the United States ior (0% to 7%). 3 Often, sexual contacts of persons with high-Public Health Service has estimated that the likelihood of risk behavior partake in high-risk behavior as well. Thus, in perinatal infection is low, on the order of 5% to 6%, and that some of the populations evaluated for sexual transmission of breast feeding does not increase the risk of HCV infection in HCV infection, concomitant percutaneous exposures, such infants of mothers with hepatitis C. Current data do not supas injection drug use, tattoos, transfusion history, etc, conport household exposure as a risk for HCV infection. (HEPAtribute to HCV exposure (Table 1). 4-10 TOLOGY 1997;26(Suppl 1):66S-70S.)
Still, in some studies, the rate of HCV infection was found to be higher in persons with frequent, multiple sexual part-Compared with the level of viremia in patients with ners, independent of other potential risk factors. In a survey chronic hepatitis B, the level of viremia in patients with hepaof patients who presented to a Baltimore emergency departtitis C virus (HCV) infection is relatively low. This difference, ment, the frequency of anti-HCV was high: 18%. 11 The freby many orders of magnitude, between the concentration of quency in homosexual men was 21%, not substantially differcirculating virus translates to less efficient person-to-person ent from the figure in the entire group, and the frequency was much lower, 6%, for those with heterosexual exposure to a partner with high-risk behavior for blood-borne infection. These findings did not point toward sexual exposure as a Abbreviations: HCV, hepatitis C virus; anti-HCV, antibody to HCV; HIV, human immunodeficiency virus; HBV, hepatitis B virus; anti-HIV, antibody to HIV. potential risk factor for HCV infection; however, the fre-From the Gastrointestinal Unit (Medical Services) and the Liver-Biliary-Pancreas quency of anti-HCV in the subset of black men between the Center, Massachusetts General Hospital and the Department of Medicine, Harvard ages of 35 and 44 years was 51%. Although injection drug