Simulation Modelling Techniques of HIV/AIDS

AIDS incubation period as a key epidemiologic descriptor has been discussed in Chap. 1. A contrasting feature of HIV syndrome in relation to other infectious diseases is its incubation period which is a random variable and probably the longest one. An HIV infected exhibits disease symptoms after completion of this period and thereafter presents an AIDS case. The levels of CD4 T lymphocyte immune cells and HIV RNA in the human body determine the progression of the infection. HIV spread mechanism and its manifestation to AIDS are random phenomena, and hence stochastic modelling is expected to be a better descriptor of the scenario. The present chapter (i) highlights some stochastic features of HIV spread, (ii) discusses the applicability of a few well-known probability models to cover the essence of immune system failure mechanism, (iii) proposes a model for time to AIDS onset, and (iv) examines the applicability of two standard stochastic models in the AIDS situation.