AIDS

            
             AIDS is the more evolved, life threatening, form of HIV. AIDS stands for Acquired Immunodeficiency Syndrome. The name comes from the fact that HIV severely damages the immune system, the body's most important defense against disease. .
             History of AIDS.
             Scientists are not certain how, when, or where the AIDS virus evolved and first infected people. Researchers have shown that HIV-1 and HIV-2 are more closely related to simian immunodeficiency viruses, which infect monkeys, than to each other. Thus, it has been suggested that HIV evolved from viruses that originally infected monkeys in Africa and was somehow transmitted to people. .
             Scientists believe HIV infection became widespread after significant social changes took place in Africa during the 1960's and 1970's. Large numbers of people moved from rural areas to cities, resulting in crowding, unemployment, and prostitution. These conditions brought about an increase in cases of sexually transmitted diseases, including AIDS. HIV may have been introduced into industrialized nations several times before transmission was sustained and became widespread. .
             AIDS was first identified as a "new" disease by physicians in Los Angeles and New York City in 1980 and 1981. The doctors recognized the condition as something new because all the patients were previously healthy, young homosexual men suffering from otherwise rare forms of cancer and pneumonia. The name AIDS was adopted in 1982. Scientists soon determined that AIDS occurred when the immune system became damaged, and that the agent that caused the damage was spread through sexual contact, shared drug needles, and infected blood transfusions. .
             After HIV was isolated as the cause of AIDS in 1983 and 1984, researchers developed tests to detect HIV infection. These tests have also been used to analyze stored tissues from several people who died from the late 1950's and 1970's. Scientists have concluded that some of these people died from AIDS.