HIV and AIDS

HIV and AIDS

What is AIDS?

AIDS (acquired immune deficiency syndrome) is caused by the human immunodeficiency virus (HIV), which kills or impairs cells of the immune system and progressively destroys the body's ability to fight infections and certain cancers. HIV is most commonly spread by sexual contact with an infected partner.

The term AIDS applies to the most advanced stages of an HIV infection. Official criteria for the definition of AIDS are developed by the Centers for Disease Control and Prevention (CDC), which is responsible for tracking the spread of AIDS in the United States. The 1993 CDC definition of AIDS includes all HIV-infected people who have fewer than 200 CD4+ T cells. (Healthy adults usually have CD4+ T-cell counts of 800 or more.) In addition, the definition includes 26 clinical conditions that affect people with advanced HIV disease.

According to the CDC, at the end of 2006, an estimated 1.1 million adults and adolescents were living with HIV/AIDS in the United States. An estimated 4.3 million new HIV infections occurred worldwide during 2006, which equates to about 12,000 new infections each day. This indicates that the AIDS epidemic still rages out of control. There are 39.5 million people living with AIDS globally.