© 2009 IBM Corporation
http://www.eclipse.org/stem/
IBM Almaden ResearchIBM Haifa Research
STEM: The Spatiotemporal Epidemiological Modeler Open Source Disease Modeling Application Available Through
© 2009 IBM Corporation2
Introduction
General Information About STEM
Analysis of Seasonal Influenza Data from ICDC and Maccabi Health
Simulations based on Seasonal Flu Data
Swine Flu
Public Health Information Affinity Domain and Collaboration with MECIDS
© 2009 IBM Corporation3
STEM is Open Sourcehttp://www.eclipse.org/stem/downloads.php
© 2009 IBM Corporation4
Epidemiological Compartment Models
S E I R
Births
Deaths
S I R
Births
Deaths
Standard SEIR model Standard SIR model
S: susceptibleE: exposed but not yet infectiousI: infectiousR: recovered
STEM is a Framework
© 2009 IBM Corporation5
Swine FluHuman Flu
“Mixing Cell
The Many Vectors of Infectious Disease
© 2009 IBM Corporation6
US Counties (3109) EdgesCommon
Border Edges
Interstate Highway Edges
Air Travel Edges
© 2009 IBM Corporation7
STEM Core Integration Engine
Choice Between– Finite Difference Solver (fast, good for demos)
– Runge-Kutta-Fehlberg (RKF45) adaptive integration• Adaptive step size• Very efficient• Synchronized across threads (multi-core engine)• Accurate• Computational error is estimated and controlled and an
appropriate step size set automatically
– User Contributed Solvers
© 2009 IBM Corporation8
Goal: Evaluation of Public Health PoliciesMasks
No Air travel
Vaccinate
?
HCN/HL7
Weather
Air Traffic
Multiple parallel scenarios identically initialized from current real world conditions and simulate each simultaneously forward in time.
Masks/No Air
© 2009 IBM Corporation9
Why Open Source?Need for an International Community
Eclipse Foundation
MECIDS
iCDC
France (Government, Universities)
NorthropGrumman
University of EdinburghUC Davis
In discussion/meetings planned
UPMCPittStanfordMIT
U. Helsinki University of Vermont (UVM)
© 2009 IBM Corporation11
Simulations Based on ICDC Influenza Dataas initial condition
© 2009 IBM Corporation12
Recent H1N1 Outbreak
© 2009 IBM Corporation13
What are the parameters for the recent H1N1 outbreak
What is Ro?
Case report data not complete
What could we learn from public data– When first cases (~10) showed up in NY there were
thousands in Mexico city
– Flu in Mexico peaked shortly after spread to air transport system
Can we use the spread by air transport as an indicator for Ro ?
© 2009 IBM Corporation14
County/State National
How Many Cases had developed in Mexico when Flu first appears in NY ?
© 2009 IBM Corporation15
Time to epidemic peak [days after I(NY)>~10]
© 2009 IBM Corporation16
Example Social Distancing Scenario
• Delay in Flu with Temporary Social Distancing• Model does not include seasonal forcing
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