HIV (human immunodeficiency virus) is often spread through unprotected sex with an infected partner or through contact with contaminated blood, such as by sharing needles or syringes. Many people do not have symptoms when first infected with the virus, although some will have a flu-like illness within a month or two. Antiretroviral drugs can fight HIV infection, but they do not cure people of it or of AIDS.
AIDS (acquired immune deficiency syndrome) was first reported in the United States in 1981 and has since become a major worldwide epidemic. AIDS is caused by the human immunodeficiency virus (HIV). By killing or damaging cells of the body's immune system, HIV progressively destroys the body's ability to fight infections and certain cancers.
The term AIDS applies to the most advanced stages of HIV infection. More than 700,000 cases have been reported in the United States since 1981, and as many as 900,000 Americans may be infected with HIV. The epidemic is growing most rapidly among women and minority populations.
HIV is spread most commonly by having sex with an infected partner. HIV also is spread through contact with infected blood, which frequently occurs among injection drug users who share needles or syringes contaminated with blood from someone infected with the virus. Women with HIV can transmit the virus to their babies during pregnancy, birth, or breastfeeding; however, if the mother takes the drug AZT during pregnancy, she can significantly reduce the chances that her baby will be infected with HIV.
(Click HIV Transmission for a closer look at how the virus can be transmitted.)