HOW MANY HIV-INFECTIONS CROSS THE BISEXUAL BRIDGE - AN ESTIMATE FROM THE UNITED-STATES

Objective: Most heterosexual women with AIDS have been infected by mal e sex partners who acquired HIV via injecting drug use or sex with men . The contribution of bisexuality to heterosexual HIV however, has bee n poorly quantified. In this paper, we estimate the number of HIV infe ctions that spread from the homosexual community to women who have sex with bisexual men. Methods: We developed an HIV transmission model an d assigned values to the model's parameters using data from a probabil ity survey of US cities with a high risk of HIV. Results: We estimated that there are about 400 HIV infections transmitted annually from HIV -infected bisexual men in high-risk cities to their female sex partner s; two-thirds of these infections are transmitted to main female partn ers and one-third to casual partners. Uncertainties in the value of mo del parameters lead to variation in expected HIV infections mostly wit hin the range 200 to 600, and for one parameter up to nearly 800. Conc lusion: We conclude that transmission via bisexuality is a relatively minor component of the estimated 40 000 annual HIV infections in the U SA.