15 - Models for the Study of Infection in Populations

Abstract

This chapter provides an overview of the modeling of transmission dynamics of infectious diseases, with particular focus on the use of compartmental differential equation models, the most commonly used for such work. Broadly speaking, human infectious agents can usefully be divided into microparasites and macroparasites. There are many clinical characteristics of human infections that are relevant to modeling of infection transmission dynamics in populations and that determine whether they are endemic or epidemic. The route or routes of transmission characteristic of an infection also determine the population dynamics of an infection. Herd immunity is essentially a simple concept describing the totality of naturally acquired and vaccine-based immunity to a given infectious agent as a proportion of the whole population. Average age at infection (A) is a useful summary measure indicating the arithmetic mean age at infection of all cases over some period of time. An essential aspect of the use of mathematical models in infectious disease epidemiology is validation of model results against real data, validation here referring simply to the ability to satisfy oneself that the model results are consistent with the available data relating to the population, which is being modeled.