Exploratory Visualization of Infectious Disease Propagation

Ben Houston, NeuralsoftZack Jacobson, Health Canada

NX-Workshop on Social Network Analysis and Visualization for Public Safety

18 – 19 October 2005

Introduction

• Goal: Deliver a disease propagation modeling application based roughly on the VITA NetViz information visualization component

• Focused on application development.

• Theory is an important, but secondary, aid.

Approach

• Rapid application development– Evolutionary, circular development model.– Regular client/customer demonstration w/

feedback.– Don’t over think problems, focus on

presenting possible solution.– Often the effective solutions are only apparent

once your client sees aspects of it in front of them.

Technology

• Language: Microsoft C#

• Graphics: GDI+ or OpenGL or Direct3D

• Mathematics: custom library

Simulation Components

Agents – one agent per “individual”, intrinsic characteristics: activity level, sociability, resiliency, dynamic attributes: health, energy level, position, disease state.

Environment – infinite 2-dimensional plane. Agents are free to move. Agent-agent proximity is used to model disease exposure and transmission.

Disease Model – a state transition graph. Interaction between the agent’s intrinsic and dynamic attributes determines the progression of the disease (the speed and path through disease’s state transition graph.)

Simulation Initialization

– Population model used to initialize the intrinsic characteristics of each of the agents. Specifies “distribution” of characteristics.

– Disease model – a general disease model which via parameters specification can be used to represent diverse specific diseases.

Running the Simulation

• All data produced during the simulation is captured in an efficient compressed form in real time.

Interactive Visualization

• 3 separate synchronized views which each allow intuitive access to different data dimensions.

• Currently, only one view can be displayed on the screen at a time, but simultaneous views may be in the future.

Interactive Visualization - 1

Population Snapshot View– Overhead view of a 2D plane. The user can scroll through time to inspect specific times of interest.

Interactive Visualization - 2

Agent-Agent Transmission Graph – The implicit social network created by tracking agent-agent infections.

Interactive Visualization - 3

Population Attribute vs. Time Charts -- Population statistics. Useful for finding minimal, maximal points or slopes.

Demonstration and Discussion

– How do features of interest in one view appear on the other views?

– Allow exploratory modification of the simulation to allow testing of containment strategies.

– Currently we are just sampling one population from the population distribution – it may be useful to automatically sample many representative populations to find a mean.

– Increase complexity of the environment (barriers, transmission modifiers), and agent behavior.

– Can this tool (or a further evolution of it) be useful in a war room scenario to help responders? If so how? If not why?