© 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