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

Many people do not develop any symptoms when they first become infected with HIV. Some people however have a flu like illness within a month or two after being exposed. Other symptoms would include enlarged lymph glands, tiredness, fever, loss of appetite and weight, diarrhea, yet infections of the mouth and vagina, and night sweats. Also often getting many bacterial infections like infections of the intestinal track, lungs, brain, eyes, and other organs. Cancers are also signs of HIV, due to the fact that your immune system is down.

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.

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