Acquired Immunodeficiency Syndrome (AIDS) is caused by a retrovirus, which is known as the Human Immunodeficiency Virus (HIV). The major characteristics of HIV infection are a deterioration of the immune system, risk for opportunistic infections and malignancies, and eventually death.

Today AIDS is a major threat to the world’s population. It has killed more than 25 million people since it was first recognized in 1981, making it one of the most destructive epidemics in recorded history. Despite recent, improved access to antiretroviral treatment and care in many regions of the world, the AIDS epidemic claimed 3.1 million lives in 2005; more than half a million were children. The total number of people living with HIV reached 40.3 million people. Close to 5 million people were newly infected with the virus in 2005. The highest burden of HIV/AIDS is in sub-Saharan Africa, where also many other infectious diseases like malaria and TB are prominent. Co-existence of infections is often referred to as “double-trouble” and is unique to the African context but their interaction at all levels is largely unexplored.

Antiretrovirals (ARV) have proved very effective at treating people with AIDS. But they are not a cure. If treatment is discontinued the virus becomes active again, so a person on ARVs must take them for life. Although the price of ARVs has plummeted, their cost remains an obstacle to access in the developing world. ARVs drastically increase life expectancy and decrease vertical transmission. This will ultimately have an impact on sexual and contraceptive behaviour, sexually transmitted infections and (un)intended pregnancies.