DISCUSSION selleckchem Our failure to find a significant relation between risky sexual behavior and anti-HCV status after we adjusted for injection drug use illustrates the extent to which the relationship between risky sexual behavior and anti-HCV positivity is confounded by drug use in STD populations. This raises the possibility that previous reports of an independent relation between risky sexual behavior and HCV infection may be attributable in part to incomplete ascertainment of injection drug use. In studies of both STD clinic clients9 and blood donors,23 a number of respondents who denied injection drug use prior to HCV diagnosis later admitted it. The fact that multiple methods of assessment were used to increase ascertainment of injection drug use in our sample may have contributed to our finding that injection drug use accounted for much of the relation between risky sexual behavior and HCV infection.

Measures of exposure to blood or sores during sexual activity were weakly related to anti-HCV status, even at the univariate level, failing to support our hypothesis that such exposure might serve as a possible mechanism for sexual HCV transmission. More important, we did find evidence to support our hypothesis that HCV transmission may take place between sexual partners via exposure to bleeding caused by intimate partner violence. The significance of this association is enhanced by the fact that it was robust, surviving adjustment for a wide array of competing parenteral and sexual risk factors in analyses both including and excluding injection drug users.

In addition, the association between HCV infection and bleeding caused by intimate partner violence remained significant even after we controlled for measures of intimate partner violence itself, indicating that the association is specific to intimate partner violence that causes bleeding. The specificity of the association with bleeding is consistent with a plausible explanation for how transmission of a blood-borne virus could take place in the context of intimate partner violence. Intimate partner violence is often reciprocal, and reciprocal violence is more likely to result in injury.24 If reciprocal injuries cause bleeding by both partners, an exchange of blood that could transmit virus may take place.

The feasibility of such transmission is supported by a documented instance in which phylogenetic analysis was used to link an acute HCV infection after a bloody fist fight Carfilzomib to an undiagnosed chronic case of HCV in the other combatant.18 Although the relative risk of HCV infection associated with exposure to bleeding caused by intimate partner violence is substantially smaller than that associated with injection drug use, its importance is increased by the fact that bleeding caused by intimate partner violence is substantially more prevalent than injection drug use.