Transmission (HIV) occurs through exposure to infected bodily fluids, including blood, blood products, semen, and genital secretions. Exposure to blood or blood products has been associated with HIV infection among intravenous drug users, persons receiving transfusions, and hemophiliacs. Although the prevalence of infection continues to increase among intravenous drug users, blood products are now safe as a result of blood donor counseling, screening of donors for HIV antibodies, and heat treatment of clotting factor concentrates. Sexual contact, both homosexual and heterosexual, continues to be the predominant mode of HIV transmission among adults. Heterosexual transmission predominates in Africa and the Caribbean and is becoming relatively more important elsewhere as well, as transmission by homosexual contact may be decreasing.
Early during the epidemic of acquired immunodeficiency syndrome (AIDS), it was recognized that HIV infection was associated with sexual promiscuity and with a high incidence of other sexually transmitted diseases (STDs) among sexually