The first recognised cases of the acquired immune deficiencysyndrome (AIDS) occurred in the summer of 1981 in America.Reports began to appear of Pneumocystis carinii pneumonia andKaposi’s sarcoma in young men, who it was subsequentlyrealised were both homosexual and immunocompromised. Eventhough the condition became known early on as AIDS, itscause and modes of transmission were not immediatelyobvious. The virus now known to cause AIDS in a proportionof those infected was discovered in 1983 and given variousnames. The internationally accepted term is now the humanimmunodeficiency virus (HIV). Subsequently a new variant hasbeen isolated in patients with West African connections –HIV-2.The definition of AIDS has changed over the years as aresult of an increasing appreciation of the wide spectrum ofclinical manifestations of infection with HIV. Currently, AIDSis defined as an illness characterised by one or more indicatordiseases. In the absence of another cause of immune deficiencyand without laboratory evidence of HIV infection (if thepatient has not been tested or the results are inconclusive),certain diseases when definitively diagnosed are indicative ofAIDS. Also, regardless of the presence of other causes ofimmune deficiency, if there is laboratory evidence of HIVinfection, other indicator diseases that require a definitive, orin some cases only a presumptive, diagnosis also constitute adiagnosis of AIDS.In 1993 the Centers for Disease Control (CDC) in the USAextended the definition of AIDS to include all persons who areseverely immunosuppressed (a CD4 count <200>
