modeling the ebola outbreak in west africa, 2014

Modeling the Ebola Outbreak in West Africa, 2014

August 19th Update

Bryan Lewis PhD, MPH (blewis@vbi.vt.edu)Caitlin Rivers MPH, Eric Lofgren PhD, James Schlitt, Katie Dunphy,

Stephen Eubank PhD, Madhav Marathe PhD, and Chris Barrett PhD

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Currently Used WHO DataCases Deaths

Guinea 607 406

Liberia 1082 259

Sierra Leone 910 392

Nigeria 16 5

Total 2615 1427

● Data reported by WHO on Aug 22 for cases as of Aug 20

● Sierra Leone case counts censored up to 4/30/14.

● Time series was filled in with missing dates, and case counts were interpolated.

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Epi Notes – WHO reports

• Unsettling Underestimation assessment http://www.who.int/mediacentre/news/ebola/22-august-2014/en/

– Significant undercounting of cases suspected• Lots of fresh graves in villages with no reported cases• ETCs overwhelmed in hours, non-ETC triage centers getting

flooded with patients• Large swaths of areas blockaded off with rumors of infections

• Healthcare worker impact http://www.who.int/mediacentre/news/ebola/25-august-2014/en/

– 240 HCW infected, 120 dead– Depleting the workforce, estimate 1-2 docs /100K pop– Liberian doctor Borbor dies after Zmapp Rx– First WHO HCW infected (Brit already back in UK)

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Epi Notes

• Travel restrictions (flight bans) increasing– Limiting WHO’s ability to bring in staff– Addressing a very small risk and counter productive

• WHO tweet (8-25 @4pm)– 100 more confirmed cases than previously reported

as of 8-20 (16 additional deaths)– Maybe a reporting artifact from more tests

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Epi Notes

• Outbreak in DRC– Dozen or so suspected cases a couple confirmed positive– Confirmed evidence that it is NOT related to West

African outbreak, different strain• Supplies are arriving!– 16 tons of USAID supplies https://twitter.com/theOFDA/status/503625464049856513)

– 68 tons of UNICEF supplies (http://www.unicef.org/media/media_74868.html)

– Many other smaller ones like: 30k lbs from Fort Worth http://www.star-telegram.com/2014/08/25/6066313/planeload-of-ebola-supplies-leaving.html

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Tweet volume

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Liberia Forecasts

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Liberia Forecasts

rI: 0.95rH: 0.65rF: 0.61R0 total: 2.22

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Liberia Forecasts8/6 – 8/12

8/13 – 8/19

8/20 – 8/26

8/27 – 9/02

9/3 – 9/9

Actual 163 232 296 -- --

Forecast 133 176 234 310 410

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Liberia Vaccinations

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Liberia – Better Isolation

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Liberia – Better Contact Tracing

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Sierra Leone Forecasts

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Sierra Leone Forecasts

rI:0.85rH:0.74rF:0.31R0 total: 1.90

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Sierra Leone Forecasts8/6 – 8/12

8/13 – 8/19

8/20 – 8/26

8/27 – 9/02

9/3 – 9/9

Actual 143 93 100 -- --

Forecast 135 168 209 260 324

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Sierra Leone Vaccinations

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Sierra Leone – Better Isolation

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Sierra Leone – Better Contact Tracing

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All Countries Forecasts

rI:0.85rH:0.74rF:0.31Overal:1.90

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Guinea, Sierra Leone, and Liberia8/3 – 8/9

8/10 – 8/16

8/17 – 8/23

8/24 – 8/30

8/31 – 9/6

Actual 346 231 442 -- --

Forecast 276 330 393 470 561

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Why now? What is different• Role of chance not to be discount– Running expt to look at expected outcome in this pop

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Next Steps

• Data pouring in:– Landscan– Tribal Distributions– Road networks– Procedural info for delivery of care and diag etc.

• Initial version of Sierra Leone constructed– Tests to verify and validate– Begin simulations

• Build similar versions for other affected countries

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Next Steps

• Mobility data from Flowminder– Under Analysis to compare with our estimates

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Next steps

• Publications– One planned for submission– 2 quick communications in prep

• Problems appropriate for agent-based approach– Logistical questions surrounding delivery and use of

medical supplies– Effects of limited HCW both direct and indirect– Synthetic outbreaks to compare to what we’ve

observed of this one, to estimate true size