title: Geographically weighted discriminant analysis of environmental conditions associated with Rift Valley fever outbreaks in South Africa.
abstract: Rift Valley fever (RVF) is a zoonotic arboviral infection that has occurred across Africa and parts of the Middle East. Geographically weighted discriminant analysis (GWDA) is a spatially-adaptive extension of traditional discriminant analysis (DA) which has rarely been applied to infectious disease epidemiology research. This study compares the classification performance of GWDA and traditional DA when used to distinguish between locations where livestock are at risk or are not at risk for acquiring RVF virus (RVFV) using 699 case reports of RVF (affecting 18,894 animals) from two outbreaks in South Africa in 2008-2009 and 2010-2011. GWDA produced better results than traditional DA for all bandwidth and kernel combinations. The best GWDA model correctly classified 96.6% of the original data versus 84.5% obtained with traditional DA. With GWDA, false positives decreased from 10.9% to 3.7%, and false negatives decreased from 19.9% to 3.2%.
authors.affiliation: Department of Geography and GeoInformation Science, George Mason University, 4400 University Drive, MS 6C3, Fairfax, VA 22030-4444, United States. Electronic address: dennis.nicholas@faa.gov.
authors.forename: Dennis E
authors.initials: DE
authors.lastname: Nicholas
authors.affiliation: Department of Geography and GeoInformation Science, George Mason University, 4400 University Drive, MS 6C3, Fairfax, VA 22030-4444, United States. Electronic address: pdelamat@gmu.edu.
authors.forename: Paul L
authors.initials: PL
authors.lastname: Delamater
authors.affiliation: O'Brien Institute for Public Health, Cumming School of Medicine, University of Calgary, 3280 Hospital Drive NW, Calgary, AB T2N 4Z6, Canada. Electronic address: nwaters@gmu.edu.
authors.forename: Nigel M
authors.initials: NM
authors.lastname: Waters
authors.affiliation: Department of Global and Community Health, George Mason University, 4400 University Drive Fairfax, MS 5B7, Fairfax, VA 22030-4444, United States. Electronic address: kjacobse@gmu.edu.
authors.forename: Kathryn H
authors.initials: KH
authors.lastname: Jacobsen
mesh_terms: D000818:Animals; D016002:Discriminant Analysis; D004196:Disease Outbreaks / Q000706:statistics & numerical data*; D004777:Environment; D058751:Livestock / Q000382:microbiology*; D012295:Rift Valley Fever / Q000453:epidemiology*; D013019:South Africa / Q000453:epidemiology; D000068916:Spatial Regression
keywords: GWDA; Geographically weighted discriminant analysis; Rift Valley fever; South Africa