Risk behavior-based model of the cubic growth of acquired immunodeficiency syndrome in the United States.

Abstract

The cumulative number of cases of acquired immunodeficiency syndrome (AIDS) in the United States has grown as the cube of time rather than exponentially. We explain this by interactions involving partner choice and sexual frequency in a risk-behavior model with biased mixing. This leads to a saturation wave of infection moving from high- to low-risk groups. If this description is correct, then the decreasing growth rate of AIDS cases is not due to behavior changes; rather it is due to the intrinsic epidemiology of the disease.