© 2014 IBM Corporation

STEM Ebola Model

- Sensitivity of Ebola to Interventions

Kun Hu, Simone Bianco, Stefan Edlund, James Kaufman

IBM Almaden Research Center

© 2014 IBM Corporation

Introduction

Ebola virus disease (EVD)

– RNA virus of the family Filoviridae, genus Ebolavirusin

2014 Outbreak in West Africa, largest in history

– Importation to US, Spain

>10,000 infectious cases, ~5000 death

Incubation: 2~21 days

Transmission:

– Direct contact with infectious blood or body fluids

– Postmortem transmission: 2 to 5 times high

– Sexual transmission through semen

Symptoms

Basic Reproductive Number (R0): 1.3 ~ 1.8

CDC predicts > 1M cases by Jan 2015

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Model

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Model Calibration

Nelder Mead Simplex (NMS) algorithm

– normalized mean square error (NMSE)

Fitted 2 parameters

– infectious transmission rate (𝛽𝑖)

– postmortem transmission rate (𝛽𝑑)

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Model Parameters

3. CDC (2014) http://www.cdc.gov/vhf/ebola/

6. Towers S, et.al., (2014) Temporal Variations in the Effective Reproduction Number of the 2014 West Africa Ebola Outbreak. . PLOS

Currents Outbreaks 2014 Sep 18.

9. Althaus C (2014) Estimating the Reproduction Number of Ebola Virus (EBOV) During the 2014 Outbreak in West Africa. PLOS Currents

Outbreaks 2014 Sep 2.

11. Gomes, et al. (2014) Assessing the International Spreading Risk Associated with the 2014 West African Ebola Outbreak. . PLOS

Currents Outbreaks 2014 Sep 2

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Simulation

Solver:

– Runge-Kutta Cash-Karp deterministic solver

Initialization and Map:

– Guinean (2), Liberia (5) and Sierra Leone (5)

– Administrate level 0

Experimental Parameters

– Hospital admission rate (𝜏): [0,1], w/ step: 0.1

– Burial rate (𝛿): [0,1], w/ step: 0.1

– Infectious transmission rate (𝛽𝑖): [0,2] w/ step: 0.2

– Postmortem transmission rate (𝛽𝑑): [0,2] w/ step: 0.2

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Sensitivity Analysis (1)

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Sensitivity Analysis (2)

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Sensitivity Analysis (3)

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Backup Slide

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Modeling an Ebola outbreak response: STEM

Outbreaks need prompt response

Mathematical modeling of alternative scenarios

Consider air and land travel

Use reliable denominator data

Integrate datasets (humidity, temperature, wind, etc.)

Make reliable predictions at both local and global level

Free and open source (IBM to Eclipse foundation)

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African Model

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Global threat of the West Africa Ebola outbreak

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