Jill Bigley Dunham (2005)
An Agent-Based Spatially Explicit Epidemiological Model in MASON
Journal of Artificial Societies and Social Simulation
vol. 9, no. 1
<http://jasss.soc.surrey.ac.uk/9/1/3.html>
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Received: 02-Feb-2005 Accepted: 15-Dec-2005 Published: 31-Jan-2005
Figure 1. A flowchart of possible states in an epidemic model |
Figure 2. Two-layered network (Bian 2004) |
Figure 3. Simulation display window. Susceptible agents are shown in green, exposed in blue, infected in red, and removed in black |
Table 1: Basic simulation parameters | ||
Parameter | Default Value | Description |
XMIN | 0 | Controls display size and shape |
XMAX | 800 | Controls display size and shape |
YMIN | 0 | Controls display size and shape |
YMAX | 600 | Controls display size and shape |
DIAMETER | 8 | Physical size of agents |
NUM_HUMANS | 40 | Total humans in simulation |
NUM_INFECTED | 5 | Number of humans initially infected |
NUM_REMOVED | 0 | Number of humans initially removed |
NUM_EXPOSED | 0 | Number of humans initially exposed |
DAY_LENGTH | 500 | Number of time steps per simulation day |
Table 2: Disease-specific simulation parameters | ||
Parameter | Default Value | Description |
SIR_MODEL | True | Flag to indicate inclusion of removed state. |
SEIR_MODEL | False | Flag to indicate inclusion of exposed/latent state. |
INFECTION_DISTANCE | 20 | Radius of infectiousness |
MEAN_INFECTED_TIME_DAYS | 1.0 | |
MAX_INFECTED_TIME_DAYS | 1.0 | |
MIN_INFECTED_TIME_DAYS | 1.0 | |
MEAN_EXPOSED_TIME_DAYS | 1.0 | |
MAX_EXPOSED_TIME_DAYS | 1.0 | |
MIN_EXPOSED_TIME_DAYS | 1.0 | |
INFECTIVITY_RATE_EXPOSED_DAYS | 0.75 | |
INFECTIVITY_RATE_DAYS | 0.5 | |
Table 3: Societal and personal simulation parameters | ||
Parameter | Default Value | Description |
health_factor | Between 0 and 1 | Index of a human''s general health |
ACCEPTANCE | 0.5 | Likelihood of taking a sick day when ill |
HOME_MEAN | 2.59 | Mean home size |
HOME_SD | 1.42 | Standard deviation of home size |
WORK_MEAN | 10 | Mean workplace size |
WORK_SD | 3.5 | Standard deviation of workplace size |
Figure 4. The simulation console |
Alternatively, simulation parameters can be specified using an input file. Using the input file allows control over the full set of parameters, including setting maximum and minimum exposed and infection lengths to allow variable lengths for these phases. Home and workplace size distributions can also be varied using input files.
Figure 5. Human behavior rules |
Figure 6. Infection behaviors |
Figure 7. Movement through the infection phases |
Table 4: Some parameters used for influenza-like epidemic demonstration |
INFECTION_DISTANCE =20 DAY_LENGTH =1000 MEAN_INFECTED_TIME_DAYS=5.0 MAX_INFECTED_TIME_DAYS=6.0 MIN_INFECTED_TIME_DAYS=4.0 INFECTIVITY_RATE_DAYS=0.2f MEAN_TIME_EXPOSED_DAYS=2.0 MAX_TIME_EXPOSED_DAYS=5.0 MIN_TIME_EXPOSED_DAYS=1.0 INFECTIVITY_RATE_EXPOSED_DAYS=0.3f NUM_HUMANS =100 NUM_INFECTED =0 NUM_REMOVED =0 NUM_EXPOSED =2 ACCEPTANCE =0.5f SIR_MODEL =1 SEIR_MODEL =1 |
Figure 8. Flu-like epidemic |
Table 5: Some parameters used for RSV-like epidemic demonstration |
INFECTION_DISTANCE =20 DAY_LENGTH =1000 MEAN_INFECTED_TIME_DAYS=8.0 MAX_INFECTED_TIME_DAYS=10.0 MIN_INFECTED_TIME_DAYS=6.0 INFECTIVITY_RATE_DAYS=0.25f MEAN_TIME_EXPOSED_DAYS=5.0 MAX_TIME_EXPOSED_DAYS=8.0 MIN_TIME_EXPOSED_DAYS=2.0 INFECTIVITY_RATE_EXPOSED_DAYS=0.25f NUM_HUMANS =100 NUM_INFECTED =0 NUM_REMOVED =0 NUM_EXPOSED =2 ACCEPTANCE =0.7f SIR_MODEL =0 SEIR_MODEL =1 |
Figure 9. RSV-like epidemic |
Table 6: Some parameters used for Lassa-like epidemic demonstration |
INFECTION_DISTANCE =10 DAY_LENGTH =1000 MEAN_INFECTED_TIME_DAYS=10.0 MAX_INFECTED_TIME_DAYS=20.0 MIN_INFECTED_TIME_DAYS=5.0 INFECTIVITY_RATE_DAYS=0.15f MEAN_TIME_EXPOSED_DAYS=10 MAX_TIME_EXPOSED_DAYS=21.0 MIN_TIME_EXPOSED_DAYS=6.0 INFECTIVITY_RATE_EXPOSED_DAYS=0.35f NUM_HUMANS =100 NUM_INFECTED =0 NUM_REMOVED =0 NUM_EXPOSED =2 ACCEPTANCE =1.0f SIR_MODEL =1 SEIR_MODEL =1 |
Figure 10. Lassa-like epidemic demonstration |
Figure 11. Flu-like epidemic using infection pull instead of push |
Figure 12. Revised infection flowchart |
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