1The Demographic Impact of HIV/AIDS

It is now 20 years since the first cases of acquired immune deficiency syn-drome (AIDS) were discovered in sub-Saharan Africa. At the beginning of the third decade of the global pandemic, AIDS has reversed gains in life expectancy and improvements in child mortality in many countries; mor-tality among the population aged 15–49 has increased manyfold, even in countries with modest epidemics.1 AIDS is the leading cause of mortality among adults (WHO, 2004). According to estimates by the Joint United Nations Programme on AIDS (UNAIDS), as of the end of 2003, over 20 million people had died of AIDS. Some 38 million people are estimated to be living with the human immunodeficiency virus (HIV), the virus that causes AIDS, the overwhelming majority of whom—over 90 percent—are in the developing world. In the absence of drug therapy, survival with HIV/AIDS is estimated to be around 10 years. Because of this lag between infection and death, the deaths of those who were infected with HIV in the early 1990s are ampli-fying mortality rates today. In sub-Saharan Africa the increase in mortal