This is a short (15 min.) presentation I just gave on agent-based models for wildlife epidemiology.

1. Agent-based Modeling, Functional
Connectivity, and Disease
Transmission in Felines
Jeff A. Tracey, PhD
Sue VandeWoude, PhD
Kevin R. Crooks, PhD
Colorado State University

2. Introduction
● Agent-based Modeling (ABM)
● Role of host behavior in the ecology of
infectious disease
– Movement and contact
– Habitat fragmentation due to urbanization

3. Our Study System
● Species:
– Bobcats (Lynx rufus), mountain
lions (Puma concolor), domestic
cats (Felis catus)
● Locations:
– Southern California, Colorado,
Florida, ...
● Diseases:
– FIV, plague, calicivirus,
toxoplasmosis, others

4. Bobcats in Southern California
HABITAT
BOBCAT
NON-HABITAT

5. Questions
● How does movement behavior interact with
habitat fragmentation to affect contact rates
and spread of an SI disease?
● How does movement behavior and landscape
structure affect the transmission of the disease
within and between habitat patches?

6. Agent-based Models (ABMs)
● a.k.a. Individual-based Models (IBMs)
● Agent-level:
– Individual bobcats
– Sensing, decisions, behavior
– Interactions
● System-level: emergence; collect data, summarize
● “Computational laboratories”

7. Start Simple...
● No birth, death, or life history
● No social interactions
● Agents have same move rule
● Simple SI, direct contact disease (FIV-like)
● Incrementally, we will add detail / specificity

8. ABM Components
● Landscape
● Agents
● Disease
● Networks
– Contact
– Disease
– Later, will add social networks

9. Low Habitat Amount High
High
Fragmentation
Low

10. Movement Rules
● Parts of movement rule
– Landscape response
– Basic movement rule
● Basic movement rules:
– Random
– Home range-like
– Dispersal-like
● More realistic rules...

11. Simulation Experiments
● Vary parameters
– Disease
● Proportion of initially infective individuals
● Probability of disease transmission
– Landscape
● Amount of habitat
● Fragmentation
– Movement
● Non-habitat preference
● Move rule and parameters

12. Agent Locations and State

13. Contact Network

14. Disease Network

15. Simulation Experiments
● Summarize system-level properties:
– Proportion infective at end of simulation
– Proportion of within-patch transmissions
– Proportion of between-patch transmissions
– Proportion of patches with infective individuals
– many others...

16. Movement Behavior Matters
10 % Habitat 30 % Habitat
Variation Due to
Movement Behavior Only
Variation Due to
Movement Behavior Only

17. Effects of Movement Can Be
Nonlinear
Example: Between Landscape: highly fragmented, 30% habitat
patch transmission
Highest at:
● Intermediate non-
habitat permeability
● Intermediate
directionality for
dispersal-like
movement
Directionality

18. Fragmentation Does Not Always
Slow Disease Spread
● Effects of Dispersal-like Movement
50 % Habitat
landscape can
have opposite
effects on
prevalence
depending on
movement

19. Landscape Change as a Dynamic
Process
● Therefore:
– Connectivity and
movement should
change
– Disease dynamics
should change
● More vulnerable at Western Futures Models
Dr. Dave Theobald, CSU
particular stages?
● Species-specific

20. Landscape Change as a Dynamic
Process
● Therefore:
– Connectivity and
movement should
change
– Disease dynamics
should change
● More vulnerable at Western Futures Models
Dr. Dave Theobald, CSU
particular stages?
● Species-specific

21. Landscape Change as a Dynamic
Process
● Therefore:
– Connectivity and
movement should
change
– Disease dynamics
should change
● More vulnerable at Western Futures Models
Dr. Dave Theobald, CSU
particular stages?
● Species-specific

22. Landscape Change as a Dynamic
Process
● Therefore:
– Connectivity and
movement should
change
– Disease dynamics
should change
● More vulnerable at Western Futures Models
Dr. Dave Theobald, CSU
particular stages?
● Species-specific

23. Important Points:
● Agent-based modeling approach
– Computational laboratory
● Movement matters
– Can be nonlinear, counter-intuitive
● Simulation software

24. Acknowledgments
Funding: Dr. Jun Zhu (UW-Madison/CSU)
● National Science Collaborators From:
Foundation
● UC Davis, University of Florida, San Diego
● Burroughs Wellcome State University, US Geological Survey, NIH,
Travel Scholarship CDC, NPS, USFWS, Colorado Division of
Wildlife
Other CSU Team
Members:
● Mo Salman, Mike Lapin Thank you to the conference organizers!
● Sarah Bevins
● Justin Lee, Jesse Lewis,
Martha MacMillan, Linda
Sweanor, Robert Alonso

25. Thanks
Website: http://feline-eid.colostate.edu
E-mail: jatracey2005@gmail.com