6 per 10,000 person-years (95% CI, 0 0-7 7) (minimum estimate) to

6 per 10,000 person-years (95% CI, 0.0-7.7) (minimum estimate) to 7.2 per 10,000 person-years (95% CI, 1.3-13.0) (maximum estimate). The estimated risk per

sexual contact ranged from 1 per 380,000 (95% CI, 1/600,000-1/280,000) to 1 per 190,000 (95% CI, 1/1.03 million to 1/100,000). Concordantly infected couples were no more likely to share blood-contaminated objects, such as nail clippers, razors, and toothbrushes, than couples in which one partner remained uninfected (0.0% versus 10.1%, P = 1.00), but were more likely to have vaginal intercourse during menses (100.0% versus 65.6%, P = 0.55) and anal intercourse (66.7% versus 30.2%, P = 0.22), and were less likely to use condoms (0.0% selleck versus 30.4%, P = 0.56). These differences, however, were not statistically significant. Sexual transmission of HCV among monogamous heterosexual

couples is an extremely infrequent event. SCH772984 cell line The maximum prevalence of HCV infection among sexual partners of subjects with chronic HCV infection was only 1.2%, and the maximum incidence of HCV transmission by sex was 0.07% per year or approximately one per 190,000 sexual contacts. Condom use was infrequent among the study participants and decreased over the duration of the sexual relationship, indicating that the very low rate of sexual transmission in our study population was not due to use of barrier methods during sexual activity. This estimate includes couples who were antibody-concordant by serotyping assays but without confirmation of HCV strain relatedness by phylogenetic

analysis because at least one of the partners was HCV RNA–negative. By including these couples, we minimized selection bias, but because couples with the same genotype/serotypes may not be infected with the same strain of HCV, we provided maximum (including aviremic serotype concordant couples) and minimum (based on viremic couples only) estimates of HCV prevalence and incidence. The minimum estimate of prevalence of HCV infection among viremic couples was 0.6% (95% CI, 0.0%-1.3%) and the incidence was 0.04% per SPTBN5 year. Sexual transmission of HCV presumably occurs when infected serum-derived body fluids are exchanged across mucosal surfaces. Potential factors that may influence this exchange include the titer of virus, the integrity of the mucosal surfaces, and the presence of other genital infections (viral or bacterial). Studies to detect HCV RNA in semen (seminal fluid and cells), vaginal secretions, cervical smears, and saliva have yielded mixed results.14-20 Failure to detect HCV RNA in body secretions from chronically infected subjects may be due to technical factors (e.g., specimen collection and storage) and the inability to exclude cellular components and to overcome the presence of polymerase inhibitors in body fluids.

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