Biology Reference
In-Depth Information
Susceptible
Host
Exposed
Host
Infectious
Host
Recovered
Host
Birth
Death
Death
Death
Death
Infectious
Vector
Exposed
Vector
Susceptible
Vector
Birth
Death
Death
Death
Figure 3.2
SEIR model for vectorborne disease. Transmission occurs in two ways: from vector to the pri-
mary host and conversely.
follows seasonal trends, such as influenza, one of the common approaches
to modeling such conditions is the use of a forcing function in the trans-
mission parameter, β. Dusthov et al. (2007) demonstrated this for influenza
where he produced a persistent oscillation in the number of the infected
individuals.
By using the compartmental division, the SEIR method model assumes
that every individual in each category is homogenous. For example, all sus-
ceptible individuals are equally prone to the disease, regardless of their
genetic composition or comorbidity. Furthermore, this deterministic model
describes average or typical behavior of the population in each category.
3.5.2.2 Agent-Based Simulation
The Agent-Based Model (ABM) or individual-based model is a computing-
intensive model that concurrently simulates a set of interacting individu-
als and is widely used to represent social networks. The individual can
represent the host, vector, or a collection of hosts such as a farm. Unlike
SEIR, ABM is capable of capturing the heterogenic properties of individu-
als and their associated spatial landscapes. In addition, ABM can take into
account movements between individuals and represent transmission as
being dependent on distance. Overall, ABM provides great flexibility in
terms of representing a biologically realistic system. However, the more
details included in the model, the greater the increase in both the number
of parameters in the model as well as in the efforts needed to estimate these
parameters.
Keeling et al. (2001) demonstrate the use of ABM for the spread of foot-
and-mouth disease in the United Kingdom. Here, the individuals repre-
sent farms, which are categorized as susceptible, exposed, infectious, or
recovered. With the model considering the dynamics of the disease spread
