Epidemiology

Despite tremendous progress in our understanding of the HIV virus, its mode of transmission, and treatments to prevent its progression, HIV disease continues to be pandemic. Worldwide, an estimated 4.8 million people became newly infected in 2003 and more than 20 million people have died since the first cases of acquired immune deficiency syndrome (AIDS) were identified in 1981. An estimated 1,106,400 persons in the United States were living with HIV infection, with 21% undiagnosed and unaware of their infection at the end of 2006. In 2007, the estimated number of persons diagnosed with AIDS in the United States was approximately 37,041.

Most new HIV infections still occur among men who have sex with men (MSM). The Centers for Disease Control and Prevention (CDC) estimated that approximately 56,300 people were newly infected with HIV in 2006, with over half of these new infections occurred in gay and bisexual men. Black/African American men and women were strongly affected, and were estimated to have an incidence rate that was 7 times as high as that among whites. At the end of 2007, the estimated number of persons, adults and children, living with HIV/AIDS in the United States with confidential name-based HIV/AIDS infection reporting was 571,378. The estimated number of deaths of persons with AIDS in the United States through 2007 was 583,298.

Highly active antiretroviral therapies (HAART) and prenatal detection of HIV-infected women has caused the rates of congenitally acquired HIV to decline dramatically in developed countries, though rates remain high in less developed nations. Only 9300 cases of AIDS in children younger than 13 years were reported in the United States at the end of 2002, and only 59 cases of congenitally acquired cases were reported to the CDC in 2003. Since the advent of HAART, children acquiring HIV through vertical transmission are living longer and are now young adults, living with a chronic condition. Many of these young adults are attending college, are working, and are now beginning to have their own children.

Although new case rates for congenitally acquired HIV are low, many young people are acquiring HIV disease. Of new HIV infections reported to the CDC, adolescents account for 50% as well as 25% of new sexually transmitted diseases reported annually to the CDC. Infection rates among adolescents in the United States are increasing. The most common modes of transmission among adolescents and young adults was male to male sexual transmission, accounting for 42% of all cases; high-risk heterosexual contact accounted for 31%, and injection drug use 21%. The highest rates of new infections were among African Americans, and 19% were among Hispanics. HIV infection is a growing problem among adolescents, especially minority adolescents, emphasizing the importance of prevention efforts focused on the adolescent population.