AIDS is the Acquired Immune Deficiency Syndrome. This is an advanced stage of HIV infection presenting with serious clinical illness. It presents in both adults and children in many different ways. The main feature of AIDS is severe damage to the immune system leading to many viral, bacterial and fungal infections, many of which do not usually occur in people with a healthy immune system. These are called HIV associated infections or opportunistic infections. They take the ‘opportunity’ of infecting people with poor immune function (immune deficiency). At present AIDS can be controlled but cannot be cured. If not treated with antiretroviral drugs, AIDS is a fatal condition.