Many sub-Saharan African countries are confronted by the HIV/AIDS epidemic. This article reviews academic literature in the social sciences and health to discover why HIV/AIDS has become an epidemic in sub-Saharan Africa and not in other parts of the world. This was studied by examining the social determinants of diminishment of tradition and social cohesion in terms of political, social and economic problems. Four countries in this region were selected for this case study, namely South Africa, Botswana, Uganda and Zimbabwe. The findings showed that instability in socio-economic and political aspects in these nations was responsible for creating a suitable environment for the spread of HIV/AIDS infection. This paper concludes by using the theories of collective action/responsibility and social cohesion to hypothesise that the breakdown of social ties due to various kinds of conflicts and unrest is one of the main contributors to the HIV/AIDS epidemic.