It's history, impact and current treatments.
How did it begin and spread?
A species of chimpanzee in West Africa is known as the source of the HIV infection in human bodies. The virus was most likely spread because of how humans hunted down these animals for their meat. It was transmitted when the humans came in contact with the infected blood of the chimpanzees. Then whatever the chimps were carrying (most likely simian immunodeficiency) mutated into what we call HIV today. Over several years the virus would spread all over Africa and then to the rest of the world.
Impact on the world
HIV weakens the immune system by killing off CD4+T cells which are the body's response to intruders. This leaves the body open to be attacked and this will eventually lead to AIDS.
HIV/AIDS affects the whole world and it's infection rates are increasing rapidly, currently near 42 million people are living with it.
HIV/AIDS affects every country in the world and in many infection rates are increasing rapidly. Today, an estimated 42 million people live with HIV/AIDS. Sub-Saharan Africa is the region of the world worst affected. Nearly three-quarters of persons living with HIV/AIDS (PLWHA) are in sub-Saharan Africa. Of the 3.1 million people who died of HIV/AIDS in 2002, 2.4 million were in sub-Saharan Africa. The disease has already orphaned 12 million children in Africa and that number could grow to a staggering 40 million by 2010.