"Of the estimated 398,057 male adults and adolescents living with HIV/AIDS, 64% had been exposed through male-to-male sexual contact, 16% through injection drug use, 12% through high-risk heterosexual contact, and 7% through both male-to-male sexual contact and injection drug use. Of the estimated 146,692 female adults and adolescents living with HIV/ AIDS, 72% had been exposed through high-risk heterosexual contact, and 26% had been exposed through injection drug use."

Editor's Note: The CDC defines high-risk heterosexual contact as "heterosexual contact with a person known to have, or to be at high risk for, HIV infection."

Source

Centers for Disease Control and Prevention, "HIV/AIDS Surveillance Report, 2007," Vol. 19. Atlanta: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention; 2009: p. 9.
http://www.cdc.gov/hiv/topics…