The Global Spread of HIV Infection

Subsequently, it became clear that AIDS was not a disease restricted to homosexual men, and that spread of HIV occurred via three main routes:
Sexual contact:
Especially when associated with physical abrasions.
Receptive anal sex is an extremely high risk behaviour that is not limited to homosexual men:
One study in the U.S.A. reported that 23% of single men and 20% of single women had experienced heterosexual anal intercourse at some point in their life.
Vaginal heterosexual intercourse is associated with a lower risk of contracting HIV infection.
Oral sex is associated with an extremely low risk of HIV infection.
The risk of transmission from unprotected receptive oral sex (no condom) is lower than for receptive anal intercourse using a condom.
Blood, blood-derived products and organ transplantation:
Blood transfusions not screened for HIV.
Factor VIII prepared from HIV infected blood caused AIDS in a large number of haemophiliacs prior to anonymous HIV-screening of blood donors.
Sharing of needles (contaminated with blood) amongst people who intravenously injected
Recreational drugs such as heroin.
Performance enhancing drugs (athletes).
Organ or tissue transplantation (e.g. kidney or bone marrow) from an HIV-positive donor could result in transmission to the recipient, but this mode of transfer must be considered extremely rare.
Maternal-child transmission. Approximately 42% of HIV-infected mothers pass the infection to their children via one of the three following routes:
Trans-placental infection in-utero during pregnancy.
Infection during vaginal delivery.
Infection via breast milk.
There have been incidences of HIV transmission from health care workers during therapeutic procedures, but these have been rare.
A particularly notorious case involved a dentist in Florida who infected a number of his patients, probably deliberately.
In 2001, a doctor and 6 health workers in Libya were accused of deliberately infecting 373 children with HIV. The trial is ongoing.
Identification of HIV infection as the cause of AIDS did not take long after the clinical illness was first described in 1981.
HIV-1 and HIV-2 were described in 1983 & 1985 respectively.
Some influential people still dispute that AIDS is only caused by HIV infection.
The most prominent of these is Thabo Mbeke, the President if the Republic of South Africa.
President Mbeke's beliefs have had a profound influence on how the AIDS epidemic has been managed in South Africa.
By the time that AIDS was recognized, HIV infection had already been spread around the world.
Developed countries focused on limiting the spread of HIV infection within their own communities.
Governments funded massive safer sex campaigns in the 1980s.
By comparison, little attention was given to the emerging HIV pandemic in Africa and other developing countries.
Education about safe sex remains limited in many parts of the world where HIV infection is common.
For example, 50% of women and 35% of men aged 15-19 years old living in Tanzania in 1999 did not know of ways to protect themselves against HIV/AIDS.