The accumulated evidence indicates that hepatitis C virus (HCV) can be transmitted by sexual contact but much less efficiently than other sexually transmitted viruses, including hepatitis B virus and human immunodeficiency virus (HIV). However, because sex is such a common behavior and the reservoir of HCV-infected individuals is sizable, sexual transmission of HCV likely contributes to the total burden of infection in the United States. Risk of HCV transmission by sexual contact differs by the type of sexual relationship. Persons in long-term monogamous partnerships are at lower risk of HCV acquisition (0% to 0.6% per year) than persons with multiple partners or those at risk for sexually transmitted diseases (0.4% to 1.8% per year). This difference may reflect differences in sexual risk behaviors or differences in rates of exposure to nonsexual sources of HCV, such as injection drug use or shared razors and toothbrushes. In seroprevalence studies in monogamous, heterosexual partners of HCV-infected, HIV-negative persons, the frequency of antibody-positive and genotype-concordant couples is 2.8% to 11% in Southeast Asia, 0% to 6.3% in Northern Europe, and 2.7% in the United States. Among individuals at risk for sexually transmitted diseases ( P ercutaneous exposures, such as blood transfusion and injection drug use, are well-established risk factors for hepatitis C virus (HCV) infection. The risk of HCV transmission by sexual contact, however, is less well defined. The accumulated epidemiologic evidence indicates that HCV can be transmitted by sexual contact but much less efficiently than other sexuallytransmitted viruses, including hepatitis B virus and human immunodeficiency virus (HIV).There are several case reports of acute hepatitis C occurring in persons whose only risk factor appeared to be a HCV-infected sexual partner. 1,2 The strength of these reports lay in their ability to document seroconversion in an individual at risk in temporal relationship to sexual activity with an HCV-infected partner. The mode of transmission was ascertained by carefully questioning the infected individual to exclude nonsexual sources of HCV. A high degree of sequence homology between the viral strains in the sexual partners provided virological confirmation that a transmission event had occurred.While there is sufficient evidence to support the conclusion that sexual transmission of HCV occurs, quantifying the magnitude of an individual's risk of HCV acquisition by sexual contact is more difficult. Epidemiologic studies have had several methodological shortcomings that tend to overestimate the proportion of HCV infections attributed to sexual contact. Early studies used first-generation antibody to HCV (anti-HCV) assays which have a higher false positive rate than second-and third-generation assays. Studies varied in the completeness of risk ascertainment in partners, and many failed to carefully exclude HCV acquisition from nonsexual sources (Fig. 1). Nondisclosure of injection drug use is particularly important because a...

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International Lamivudine Study Group. Lamivudine and alpha interferon combination treatment of patients with chronic hepatitis B infection: a randomised trial. Gut 2000;46:562-568 (reprinted with permission). ABSTRACT Background, aim and methods-Alpha interferon is the generally approved therapy for HBe antigen positive patients with chronic hepatitis B, but its efficacy is limited.Lamivudine is a new oral nucleoside analogue which potently inhibits hepatitis B virus (HBV) DNA replication. To investigate the possibility of an additive effect of interferonlamivudine combination therapy compared with interferon or lamivudine monotherapy, we conducted a randomised controlled trial in 230 predominantly Caucasian patients with hepatitis B e antigen (HBeAg) and HBV DNA positive chronic hepatitis B. Previously untreated patients were randomised to receive: combination therapy of lamivudine 100 mg daily with alpha interferon 10 million units three times weekly for 16 weeks after pretreatment with lamivudine for eight weeks (n ‫؍‬ 75); alpha interferon 10 million units three times weekly for 16 weeks (n ‫؍‬ 69); or lamivudine 100 mg daily for 52 weeks (n ‫؍‬ 82). The primary efficacy end point was the HBeAg seroconversion rate at week 52 (loss of HBeAg, development of antibodies to HBeAg and undetectable HBV DNA). Results-The HBeAg seroconversion rate at week 52 was 29% for the combination therapy, 19% for interferon monotherapy, and 18% for lamivudine monotherapy (p ‫؍‬ 0.12 and p ‫؍‬ 0.10, respectively, for comparison of the combination therapy with interferon or lamivudine monotherapy). The HBeAg seroconversion rates at week 52 for the combination therapy and lamivudine monotherapy were significantly different in the per protocol analysis (36% (20/56) v 19% (13/70), respectively, p ‫؍‬ 0.02). The effect of combining lamivudine and interferon appeared to be most useful in patients with moderately elevated alanine aminotransferase levels at baseline. Adverse events with the combination therapy were similar to interferon monotherapy; patients receiving lamivudine monotherapy had significantly fewer adverse events. Conclusions-HBeAg seroconversion rates at one year were similar for lamivudine monotherapy (52 weeks) and standard alpha interferon therapy (16 weeks). The combination of lamivudine and interferon appeared to increase the HBeAg seroconversion