As world population recently reached 6 billion, The Worldwatch Institute is saying that the HIV epidemic is measurably slowing population growth. Nowhere is this more evident that in sub-Saharan Africa, where of millions of people have died from AIDS and millions of others are infected with the HIV virus. AIDS has reached epidemic proportions in countries like the Congo and South Africa, where it is estimated that one fifth of their adult populations will die from AIDS, and where between one in four and one in five people are infected with the HIV virus.

While drug companies have made millions of dollars from selling high-cost medications dealing with HIV, there is still the question of how the virus was first introduced in humans.

Today we will take a look at a remarkable and controversial theory on the origins of the Human Immunodeficiency Virus (HIV) and AIDS. It holds that AIDS began after an experimental polio vaccine, known as CHAT, was administered to over one million people in Africa between 1957 and 1960. Some batches of CHAT were prepared in chimpanzee kidneys. The significance of this is that the Simian Immunodeficiency Virus (SIV) of the chimpanzee is now widely accepted as the direct ancestor of HIV-1, the virus that is said to have caused 99 percent of the world’s 15 million AIDS cases to date.

Guest:

• Edward Hooper, author of the book ??The River: A Journey to the Source of HIV and AIDS, which examines the origins of the AIDS epidemic. He is a former United Nations official and BBC correspondent in Africa, and also wrote ??Slim, an account of the AIDS epidemic.