modeling the ebola outbreak in west africa, october 15th 2014 update

DRAFT – Not for a.ribu2on or distribu2on

Op2mal Ebola Treatment Unit Placement in Liberia

Oct 15th Update

Bryan Lewis PhD, MPH ([email protected]) Caitlin Rivers MPH, Eric Lofgren PhD, James Schli,, Alex Telionis MPH,

Henning Mortveit PhD, Dawen Xie MS, Samarth Swarup PhD, Hannah Chungbaek, Keith Bisset PhD, Maleq Khan PhD, Chris Kuhlman PhD, Farzaneh Tabataba, Anil Vullikan2, Dana Kuan (DTRA)

Stephen Eubank PhD, Madhav Marathe PhD, and Chris Barre. PhD

Technical Report #14-‐111


Features of refined analysis

•  Added ODE model based burden predic2ons •  Added travel speeds to network •  Because outputs of prior work all similar: –  Focused exclusively on “Pa2ent Direct to ETU” and the LandScan™ Grid for both methods

•  Outputs include: –  Alloca2on for en2re na2on based on Popula2on (12 new centers) –  Alloca2on for northern coun2es based on Ebola Burden (6 centers) –  Alloca2on for en2re na2on based on Ebola Burden (12 centers) Ignoring 2 new centers already planned for Monrovia and Kakata


ODE Model to forecast incidence

•  Fit SEIR models to Liberian coun2es with >30 cases and >10 new cases in the last 21 days

•  Forecasted to December 1st, 2014


ODE models used to forecast incidence in 4 coun2es


Predicted Spa2al Burden


Popula2on Based Alloca2on


Burden Based Alloca2on (6)


Burden Based Alloca2on (12)


Alloca2on based on an alterna2ve method: MapOp2mizer


MapOp2mizer


Comparison of Two Methods


Future Work

•  Network reliability! – Even main roads can be washed out or impassable.

•  Place Mini-‐ETUs – 10-‐20 bed facili2es placed between main ETUs

Maryland Avenue from Pleebo to Harper (from John Etherton).


Future Work •  Itera2ve Planning approach –  Provide candidate loca2ons, model with these – As on the ground data is provided ruling out different sites, readjust and provide the next “op2mal” solu2on

•  Try other Op2mal alloca2ons: Maximum A.endance versus K-‐medians –  K-‐medians is most “equitable” solu2on –  1 person at 100 miles = 100 people at 1 mile – MA ignores those beyond distance threshold

•  Pro: maximizes availability in high density areas •  Con: ignores very remote popula2on centers


Review of briefing on October 7th

15


Features and assump2ons

•  Op2mized Loca2ons for Southeast Liberia Only – Grand Gedeh, Grand Kru, River Cess, River Gee, Maryland, and Sinoe Coun2es

•  Delivered report to DTRA on 2014-‐10-‐06 •  Limita2ons: – All roads and rivers weighted equally – Ebola case load not used – Did not include network reliability


Compe2ng Methods

•  Loca2on-‐Alloca2on – Run in Esri® ArcGIS™ 10.1 SP1 Network Analyst – Solves k-‐medians problem: places facili2es to minimize weighted travel 2me for all people

•  MapOp2mizer – Wri.en in Python using NetworkX1 Library – Solves via Dijkstra’s Algorithm2


Data Sources

•  Road Network: The Liberia Ins2tute of Sta2s2cs and Geo-‐Informa2on (LISGIS) 3 – Shapefile from John Etherton (personal communica2on)

•  River Network: Diva-‐GIS4 •  OpenStreetMap: Very detailed, but network is disconnected, and missing important rural roads

•  Popula2on: LandScan5 or WorldPop6


Prior Work

•  Eight runs of LocAll – WorldPop or LandScan ™ popula2on grids

–  “Pa2ent Direct to ETU” or “Pa2ent to Clinic to ETU”

–  Six or Seven ETUs placed – All outputs very similar

•  Two runs of MapOp2mizer –  LandScan + Direct –  Six or Seven ETUs placed


Sources 1.  Hagberg, A., Swart, P., & S Chult, D. (2008). Exploring network structure,

dynamics, and func2on using NetworkX (No. LA-‐UR-‐08-‐05495; LA-‐UR-‐08-‐5495). Los Alamos Na2onal Laboratory (LANL).

2.  Dijkstra, E. W. (1959). A note on two problems in connexion with graphs. Numerische mathema2k, 1(1), 269-‐271.

3.  Etherton, John (2014). [Personal Communica2on (2014-‐09-‐18)]. 4.  Hijmans, RJ, Guarino, L, Bussink, C, Mathur, P, Cruz, M, Barrentes, I, &

Rojas, E. (2004). DIVA-‐GIS. Vsn. 5.0. A geographic informa2on system for the analysis of species distribu2on data. Manual available at h.p://www.diva-‐gis.org.

5.  Bright, Eddie A., Coleman, Phil R., Rose, Amy N., & Urban, Marie L. (2014). LandScan 2013. In LLC UTBa.elle (Ed.), (2013 ed.). Oak Ridge, TN: Oak Ridge Na2onal Laboratory.

6.  Tatem, A.J., Gething, P.W., Bha., S., Weiss, D., & Pezzulo, C. (2014). WorldPop 2014: Pilot high resolu2on poverty maps: University of Southampton / Oxford.

modeling the ebola outbreak in west africa, october 15th 2014 update

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