The intrinsic rate of increase of HIV/AIDS: Epidemiological and evolutionary implications

A method derived from demographic theory is presented for modeling the epidemiology of an infectious disease. For long-term infections, this method better accounts for host variation in survival and transmission rates than classical compartment models. Examples of the applications of this method focus on a single long-term infectious disease, HIV/AIDS. The method is employed to examine (1) how changes in transmission rates during different stages of infection affect the rate of spread of HIV/AIDS both in wholly susceptible populations and in populations where the number of potential hosts is limited, (2) the way the relative frequencies of the different stages of infection vary over time, (3) how the rate at which the epidemic is growing (or diminishing) affects the fraction of HIV-infected individuals who manifest the symptoms of AIDS, (4) the effect of treatment on the rate of spread of HIV, and (5) the potential effects of natural selection on the virulence of HIV.