the acquired immuno-deficiency syndrome ( aids ) is widely believed to have resulted from infection by a virus known as the human immuno-deficiency virus ( hiv ). Two aids viruses have been identified so far, hiv -1 and hiv -2. It is clear that both came from Africa, where the spread of aids was first noted. While finding a cure for aids continues to be one of the main challenges for medical science, a lot of work has also gone into the question of how exactly the aids epidemic began. The most widely accepted theory is that the virus