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The burden of HIV infection and disease continues to increase in many developing countries. An emerging theme is of an HIV pandemic composed of mini-epidemics, each with its own characteristics in terms of the trends in HIV prevalence, those affected, and the HIV-related opportunistic diseases observed. A number of explanations for the observed differences in the spread of HIV infection have been proposed but since the factors concerned, such as sexual behaviour and the prevalence of other sexually transmitted diseases, are closely interrelated, it is difficult to tease out which are the most important. Among HIV-related opportunistic diseases, tuberculosis stands out as the most important cause of morbidity and mortality in most developing countries, but the relative prevalence of other diseases shows considerable regional variation. Thus, there is a need for local approaches to the global problem of managing HIV disease. The most pressing public health challenges are to use existing knowledge of strategies to reduce HIV transmission, and to apply them in ways appropriate to the local situation, and to develop, evaluate and implement interventions to prolong healthy life in those already infected.