Transmission and epidemiology of HIV/AIDS: a global view.

Since the first recognition of the condition that is now called AIDS, much has been learned. We now know that AIDS results from infection with HIV types 1 and 2. Advancements in approaches to treatment, in the form of new types of medications, have changed the trajectory of illness by slowing progression and decreasing the incidence of HIV-associated opportunistic infections in the millions of people living with HIV infection, particularly in developed countries. In less developed areas of the world, HIV infection looks different, in part because of the differential availability of medications and health care. This article focuses on epidemiology of HIV infection and AIDS in the United States and worldwide, and on transmission, including susceptibility factors.