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International journal of health geographics2007; 6; 42; doi: 10.1186/1476-072X-6-42

Using geographic information systems and spatial and space-time scan statistics for a population-based risk analysis of the 2002 equine West Nile epidemic in six contiguous regions of Texas.

Abstract: In 2002, West Nile virus (WNV) first appeared in Texas. Surveillance data were retrospectively examined to explore the temporal and spatial characteristics of the Texas equine WNV epidemic in 2002. Using Geographic Information Systems (GIS) and the Spatial and Space-Time Scan (SaTScan) statistics, we analyzed 1421 of the reported equine WNV cases from six contiguous state Health Service Regions (HSRs), comprising 158 counties, in western, northern, central and eastern Texas. Results: Two primary epidemic peaks occurred in Epidemiological (Epi) week 35 (August 25 to 31) and Epi week 42 (October 13 to 19) of 2002 in the western and eastern part of the study area, respectively. The SaTScan statistics detected nine non-random spatio-temporal equine case aggregations (mini-outbreaks) and five unique high-risk areas imbedded within the overall epidemic. Conclusions: The 2002 Texas equine WNV epidemic occurred in a bi-modal pattern. Some "local hot spots" of the WNV epidemic developed in Texas. The use of GIS and SaTScan can be valuable tools in analyzing on-going surveillance data to identify high-risk areas and shifts in disease clustering within a large geographic area. Such techniques should become increasingly useful and important in future epidemics, as decisions must be made to effectively allocate limited resources.
Publication Date: 2007-09-21 PubMed ID: 17888159PubMed Central: PMC2098755DOI: 10.1186/1476-072X-6-42Google Scholar: Lookup
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  • Journal Article

Summary

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The research article discusses how Geographic Information Systems (GIS) and Space-Time Scan statistics were used to analyse and map a 2002 West Nile Virus (WNV) epidemic among horses in six regions of Texas. The investigation aimed to identify temporal and spatial characteristics of the epidemic, as well as high-risk areas.

Research Methodology

  • In order to analyse the 2002 WNV outbreak, the researchers used Geographic Information Systems and Spatial and Space-Time Scan (SaTScan) statistics. These systems allowed them to examine spatial (area boundaries and locations) and temporal (time/date) data.
  • From the total reported equine WNV cases, the researchers considered 1421 cases from six contiguous state Health Service Regions consisting of 158 counties across western, northern, central, and eastern Texas.
  • Surveillance data of these cases were retrospectively examined to gauge the epidemic’s progression.

Study Findings

  • The analysis indicated two primary epidemic peaks: one occurred in Epidemiological week 35 (August 25 to 31) in the western part of the study area, the other in Epidemiological week 42 (October 13 to 19) in the eastern part.
  • The SaTScan statistics identified nine instances of non-random equine case aggregates (mini-outbreaks) and five unique high-risk areas across the regions studied. These were zones demonstrating a greater concentration of WNV cases which could be defined as hot spots of the WNV epidemic.

Conclusion and Implications

  • The epidemic displayed a bi-modal pattern, as there were two significant peaks of disease occurrence in 2002.
  • The use of GIS and SaTScan was instrumental in identifying, analysing, and visualising spatio-temporal patterns and high-risk hubs in the epidemic within a vast geographic area.
  • This methodology will become increasingly vital in future epidemics for making informed decisions to effectively utilise and allocate scarce resources.

In general, the research presents a potentially effective and practical method of quickly mapping and understanding disease outbreaks, allowing for more strategic resource deployment in response to public health crises.

Cite This Article

APA
Lian M, Warner RD, Alexander JL, Dixon KR. (2007). Using geographic information systems and spatial and space-time scan statistics for a population-based risk analysis of the 2002 equine West Nile epidemic in six contiguous regions of Texas. Int J Health Geogr, 6, 42. https://doi.org/10.1186/1476-072X-6-42

Publication

ISSN: 1476-072X
NlmUniqueID: 101152198
Country: England
Language: English
Volume: 6
Pages: 42

Researcher Affiliations

Lian, Min
  • Division of Modeling and Geographic Information Systems, Institute of Environmental and Human Health, Texas Tech University/TTU Health Sciences Center, Box 41163; Lubbock, TX 79409, USA. mlian@im.wustl.edu
Warner, Ronald D
    Alexander, James L
      Dixon, Kenneth R

        MeSH Terms

        • Animals
        • Cluster Analysis
        • Disease Outbreaks / veterinary
        • Geographic Information Systems
        • Horse Diseases / epidemiology
        • Horse Diseases / transmission
        • Horse Diseases / virology
        • Horses / virology
        • Population Surveillance
        • Retrospective Studies
        • Risk Assessment / methods
        • Texas / epidemiology
        • West Nile Fever / epidemiology
        • West Nile Fever / transmission
        • West Nile Fever / veterinary

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