Modeling Infectious Diseases in Humans and Animals
Matt J. Keeling & Pejman Rohani

Host Heterogeneities

The standard models introduced in Chapter 2 compartmentalize the population only in terms of infection status and history—classifying individuals as susceptible, infected, or recovered—and modeling the number of individuals in each compartment. As such, there is only one degree of subdivision within the population. In this chapter, we introduce a second degree, further dividing the population into classes with similar behavioral characteristics. These characteristics should be chosen such that all members of a class have comparable risk of both contracting and transmitting infection.

Two clear motivating examples dominate the literature of models dealing with risk:
(1) risk structure for sexually transmitted infections (STIs) and
(2) age structure for childhood infections.
Finally, we consider levels of heterogeneity within the infected class, discriminating between individuals due to the time since infection.

Program 3.1
Page 58
SIS model with high/low risk groups
Program 3.2
Page 64
SIS model with n risk groups
Program 3.3
Page 79
SIR model with children/adult age groups
Program 3.4
Page 87
SEIR model with n age groups and yearly aging.
Program 3.5
Page 94
SEIR model with multiple E and I classes.

Questions and comments to: or
Princeton University Press
Our research web pages:
Matt Keeling      Pejman Rohani