ABSTRACT
Twenty per cent of infected individuals develop Acquired Immune Deficiency Syndrome (AIDS) within five years, and 50 per cent within ten years. As with cancer, AIDS involves the immune system, although in a different manner. It is the consequence of infection by the human immunodeficiency virus (HIV) which attacks the immune system itself. In the vast majority of cases HIV infection is symptomless. HIV displays varying and occasionally protracted periods of dormancy. The trajectory for HIV infection and AIDS is so steep that estimated incidences are no sooner published than they are overtaken. Moreover, the World Health Organization (WHO) estimates that some ten million people world-wide are infected with HIV, and have revised their estimates of the cumulative disease incidence by the end of the decade from three million to four million. The WHO estimates that globally more than half a million people have contracted AIDS, although only around half that number of cases are officially confirmed.
