The interplay between demography, epidemiology and the economy: the impacts of HIV/AIDS in Sub-Saharan Africa.

During the last century Africa started to experience the Demographic Transition. In particular most Sub-Saharan African countries have already experienced a substantial decline in mortality, and have also experienced some decline in fertility. In the span of three decades of HIV pandemic the impact of AIDS on mortality, in countries with intermediate and high prevalence, has already been substantial. In high-prevalence countries life-expectancy has experienced a dramatic decline as a consequence of the super-mortality from AIDS. For instance in Botswana and Zimbabwe life expectancy declined from about 60 years in 1990 to about 35-36 years in 2005 (UNAIDS 2007). Therefore HIV/AIDS has been able to revert the level of general mortality of these populations to levels that were observed at the beginning of the DT. It is therefore trivial to remark that HIV/AIDS is, at least, substantially delaying the timing of the mortality transition in these countries. An important question is then: “to what extent can the super-mortality from AIDS affect the demographic transition and the related patterns of economic growth?”. In order to find an answer to this question we elaborated a dynamic model to simulate the impact that the interplay between the DT and HIV can have on economic growth. First we developed a demo-epidemiological model using real data to evaluate the impact of HIV on the DT under two main scenarios: A) INELUCTABLE: in this scenario we simply assume that even under circumstances of high HIV/AIDS prevalence the fertility and the mortality from causes different from AIDS are unaffected and continue their transitional trend. B) HOMEOSTATIC: even if the transition of mortality from causes different from AIDS remains ineluctable, the fertility transition is stopped by the mortality relapse, and an epoch of HIV-induced fertility relapse occurs. This is a way to incorporate the evidence (Kalemli-Ozcan 2006,2008) that the AIDS generated decline in life expectancy could lead to a potentially significant fertility relapse. Next we developed an expanded economic growth model "a la Solow" to investigate how an HIV/AIDS epidemic, affecting population growth (in particular labour force growth), could affect the process of economic growth