History, discovery, and epidemiology

On June 4, 1981, The Morbidity and Mortality Weekly Report from the Centers for Disease Control (CDC) in the United States published a report of five previously healthy young men with biopsy-confirmed pneumocystis carinii pneumonia (PCP) at three different hospitals in Los Angeles [1]. It is extremely rare for healthy young individuals to develop PCP without an underlying immunodeficiency. The single factor linking these five individuals was that they were all active homosexuals. One month later, a further report documented 26 cases of Kaposi's sarcoma, which until then had been an extremely rare tumor in the United States [2]. Again, all of the patients were young, previously healthy homosexual men. These were the first recorded reports of Acquired Immune Deficiency Syndrome (AIDS) and were quickly followed by reports of cases from other countries around the world. By September 1982, CDC had 593 reports of AIDS cases, 41% of whom were already dead. Seventy-five percent were known to be homosexual or bisexual males, and over half had PCP [3]. In 1983, workers at the Pasteur Institute identified a virus from the lymph node of an asymptomatic individual who presented with lymphadenopathy [4]. The virus replicated in culture releasing high titers of virions that contained magnesium-dependent reverse transcriptase activity and exhibited features of retroviruses on electron microscopy.