No reason for complacency about the potential demographic impact of AIDS in Africa

Much uncertainty surrounds the likely demographic impact of AIDS in the worst afflicted regions of the developing world such as sub-Saharan Africa. Various research groups have published projections of future trends but these differ widely with respect to potential impact on net population growth rates. Pessimistic forecasts suggest that AIDS may reverse the sign of a 3% to 4% population growth rate before the establishment of HIV, over time periods of a few to many decades. Optimistic forecasts suggest a decline in population growth rates, but predict that a 3% growth rate before AIDS may be reduced by only about 50% over a period of a few decades. This paper reports new analyses of the demographic impact of AIDS, based on observed age-stratified prevalences of HIV-1 infection amongst women of child bearing age. It is assumed that the observed patterns reflect the final endemic state and the implications of this assumption for adult and infant mortality and female reproductive life expectancy are assessed. It is concluded that a variety of scenarios is possible, depending on the detail of assumptions concerning life expectancy before the arrival of AIDS, the incubation period of the disease, and the rate of vertical transmission. Realistic assumptions do suggest, however, that the observed prevalences of infection in the worst afflicted regions of sub-Saharan Africa are sufficient to reduce current population growth rates to close to, or below, zero in the coming decades.