5 June 1981
On 5 June 1981, the Centre for Disease Control and Prevention (USA) reported that 5 gay men in California were suffering from a rare pneumonia (Pneumocystis carinii pneumonia or PCP). This strain of pneumonia was found in patients with weakened immune systems. These were the first 'recognised' cases of what became known as AIDS. Therefore, 1981 is therefore often referred to as the beginning of the HIV/Aids epidemic in the USA, and at this stage doctors believed that the disease only affected gay men. Later in the 1980s, a blood sample taken in the Democratic Republic of Congo back in 1959 was tested to reveal the HIV virus. This suggested that HIV/AIDS might have been introduced to humans in the 1940s or early 1950s. However, in January 2000 (San Francisco, California) the results of a new study presented at the 7th Conference on Retroviruses and Opportunistic Infections, suggested that the first case of HIV infection occurred as early as 1930. Today we know that HIV/Aids is a deadly disease that can be contracted by anyone and is currently not curable. The United Nations AIDS agency (UNAIDS) says the evidence that HIV is the underlying cause of AIDS is 'irrefutable'. HIV was isolated and identified as the source of what came to be defined as AIDS in 1983/84. HIV destroys blood cells called CD4+ T cells, which are crucial to the normal function of the human immune system. Studies of thousands of people have revealed that most people infected with HIV carry the virus for years before enough damage is done to the immune system for AIDS to develop.
References

SAHO "A history of HIV/Aids" [online] Available at: sahistory.org.za [Accessed 26 May 2009]|
Avert The Origin of HIV and AIDS [online] Available at: www.avert.org [Accessed on 5 June 2013]