Faculty Publications

Document Type

Article

Keywords

Animals, Cluster Analysis, Demography, Disease Outbreaks/statistics & numerical data, Geographic Information Systems, Humans, Incidence, United States/epidemiology, West Nile Fever/epidemiology, West Nile virus

Journal/Book/Conference Title Title

International Journal of Health Geographics

Volume

8

Issue

43

Abstract

Background: West Nile virus (WNV) is a vector-borne illness that can severely affect human health. After introduction on the East Coast in 1999, the virus quickly spread and became established across the continental United States. However, there have been significant variations in levels of human WNV incidence spatially and temporally. In order to quantify these variations, we used Kulldorff's spatial scan statistic and Anselin's Local Moran's I statistic to uncover spatial clustering of human WNV incidence at the county level in the continental United States from 2002– 2008. These two methods were applied with varying analysis thresholds in order to evaluate sensitivity of clusters identified.

Results: The spatial scan and Local Moran's I statistics revealed several consistent, important clusters or hot-spots with significant year-to-year variation. In 2002, before the pathogen had spread throughout the country, there were significant regional clusters in the upper Midwest and in Louisiana and Mississippi. The largest and most consistent area of clustering throughout the study period was in the Northern Great Plains region including large portions of Nebraska, South Dakota, and North Dakota, and significant sections of Colorado, Wyoming, and Montana. In 2006, a very strong cluster centered in southwest Idaho was prominent. Both the spatial scan statistic and the Local Moran's I statistic were sensitive to the choice of input parameters.

Conclusion: Significant spatial clustering of human WNV incidence has been demonstrated in the continental United States from 2002–2008. The two techniques were not always consistent in the location and size of clusters identified. Although there was significant inter-annual variation, consistent areas of clustering, with the most persistent and evident being in the Northern Great Plains, were demonstrated. Given the wide variety of mosquito species responsible and the environmental conditions they require, further spatio-temporal clustering analyses on a regional level is warranted.

Department

Department of Geography

Department

GeoTree Center

Comments

First published in International Journal of Health Geographics, v. 8 n.43 (Jul 2009), published by BioMed Central. DOI: doi: 10.1186/1476-072X-8-43

Original Publication Date

7-13-2009

DOI of published version

10.1186/1476-072X-8-43

Repository

UNI ScholarWorks, University of Northern Iowa, Rod Library

Date Digital

2009

Copyright

© 2009 Ramanathan Sugumaran, Scott R. Larson, and John P. DeGroote

Creative Commons License

Creative Commons Attribution 3.0 License
This work is licensed under a Creative Commons Attribution 3.0 License.

Language

EN

File Format

application/pdf

Included in

Geography Commons

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