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The acquired immune deficiency syndrome (AIDS) affects population size and composition in several ways. In particular age groups, deaths increase directly from AIDS and may also increase indirectly, as orphans, for instance, face higher mortality risks. Fertility can be affected, not only biologically but also from changes in sexual behavior. Communities may be weakened, and migration may alter the geographic distribution of the population.
This chapter draws on the work of agencies that produce global population projections to discuss the overall population effect of AIDS in Sub-Saharan African countries. It does not attempt to elucidate all the mechanisms involved—each of which deserves separate attention. Instead, the chapter focuses on the broad demographic impact. Decades after the start of the epidemics, estimates of this impact generally ignore all subtle and indirect effects and cover only the additional mortality directly from AIDS. Even this impact is highly uncertain. There is general agreement on substantial impact but no consensus on how substantial and long lasting it is.The projections of demographic impact to be considered come from three agencies: the Population Division of the United Nations (UN), the U.S. Census Bureau, and the World Bank. Each agency has produced population projections for most countries for some time. Up to 50 Sub-Saharan countries or territories are covered, although the smallest ones are left out in some data series. For at least a decade, these agencies have explicitly incorporated the effect of AIDS in selected countries. Population trends taking AIDS into account are illustrated for 2000–50 in figure 6.1, which compares results from the three agencies. An additional line represents the special UN scenario with no AIDS mortality. For Sub-Saharan Africa as a whole, the three projections of total population are well below the no-AIDS scenario practically from 2000 and fairly close to each other up to about 2015. By 2020, some divergence appears, with the Census Bureau projection 0.1 percent above the UN projection and the World Bank projection 2.5 percent below it. Divergence increases as the projections lengthen, so that by 2050 the Census Bureau projection is 8.6 percent above the UN projection and the World Bank projection is 9.4 percent below. This is the reverse of the relative impact one would expect from comparing methodologies.
