Could someone please expalin this in an easier way?? A recent issue of the Public Library of Medicine published an article speculating on what directions disease will take in the future. They compare three different scenarios: a baseline, and optimistic model and a pessimistic model. Their primary conclusion: The three leading causes of burden of disease in 2030 are projected to include HIV/AIDS, unipolar depressive disorders, and ischemic heart disease in the baseline and pessimistic scenarios. Road traffic accidents are the fourth leading cause in the baseline scenario, and the third leading cause ahead of ischemic heart disease in the optimistic scenario. Under the baseline scenario, HIV/AIDS becomes the leading cause of burden of disease in middle- and low-income countries by 2015.