A system dynamics model for AIDS policy support in Tanzania

The facts about AIDS in sub-Saharan Africa are not well known through about one third of all globally known AIDS cases is recorded in sub-Saharan Africa. In the so-called ‘pattern 2’ countries such as Congo, Rwanda, Tanzania, Uganda, Zaire or Zambia the HIV infection shows original traits which make it epidemiologically different from HIV in the United States and Europe, the ‘pattern 1’ countries. Most of the policy oriented AIDS/HIV modelling efforts have concentrated on ‘pattern 1’ countries. Yet Operational Research, with its client-oriented modelling philosophy can also offer assistance to AIDS policy makers in ‘pattern 2’ countries. Using the methods of system dynamics a detailed multi-group model of the spread of AIDS in the Tanzanian population has been developed. It is implemented on a personal computer and is capable to capturing complex virological and behavioral traits of the epidemic whilst illustrating the medical and some economic consequences in an easily conceivable graphical form. The model’s basic structure is fully described and some examples of the results are presented.