In the movie Contagion (Figure 1) a bird-flu–infected meal in Hong Kong causes a global pandemic killing millions of people. The lead actors try to trace down the source of the virus and calculate the variable R0, the basic reproduction number, to understand how fast the virus will spread.
Figure 1: Theatrical release poster for the movie Contagion.
Infectious diseases spread from human to human and can spread like wildfire. Depending on the disease, transmission can be caused by coughing, sexual intercourse, door knobs and toilet seats, and blood transfusion.
Infectious diseases are diffused through a population through the interactions of agents. In this chapter we will discuss agent-based models of infectious diseases. We will show how network structure affects the spread of the virus. Furthermore we can use the model to see the potential effects of interventions, like closing schools, to reduce the transmission of the virus.
The model we discuss in this chapter is based on a basic flu-type virus. Various other viruses contain more complex dynamics and stages of infectiousness.