Human herpesvirus 8 (HHV-8), the causal agent of Kaposi's sarcoma, is transmitted sexually among homosexual men, but little is known of its transmission among women. Although HHV-8 has been detected in blood, there has been no clear evidence of blood-borne transmission.

We identified risk factors for HHV-8 infection in 1295 women in Baltimore, Detroit, New York, and Providence, Rhode Island, who reported high-risk sexual behavior or drug use. HHV-8 serologic studies were performed with two enzyme-linked immunosorbent assays.

In univariate analyses, HHV-8 was associated with black race, Hispanic ethnic background, a lower level of education, and infection with syphilis, the human immunodeficiency virus (HIV), hepatitis B virus (HBV), or hepatitis C virus (HCV). The risk of seropositivity for HHV-8 increased with the frequency of injection-drug use (P<0.001); HHV-8 seroprevalence among the women who used drugs daily was three times that among women who never injected drugs. Among the women with a low risk of sexual transmission, HHV-8 seroprevalence was 0 percent in those who had never injected drugs and 36 percent in those who had injected drugs (P<0.001). However, injection-drug use was linked less strongly to HHV-8 infection than to infection with HBV or HCV. In a multivariate analysis, independent predictors of HHV-8 seropositivity included HIV infection (odds ratio, 1.6; 95 percent confidence interval, 1.1 to 2.2), syphilis infection (odds ratio, 1.8; 95 percent confidence interval, 1.1 to 2.8), and daily injection-drug use (odds ratio, 3.2; 95 percent confidence interval, 1.4 to 7.6).

Both injection-drug use and correlates of sexual activity were risk factors for HHV-8 infection in the women studied. The independent association of HHV-8 infection with injection-drug use suggests that HHV-8 is transmitted through needle sharing, albeit less efficiently than HBV, HCV, or HIV.