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Modelling Geographic Variations in West Nile Virus

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Abstract

Background

This paper applies a method for modelling the spatial variation of West Nile virus (WNv) in humans using bird, environmental and human testing data.

Methods

We used data collected from 503 Alberta municipalities. In order to manage the effects of residual spatial autocorrelation, we used generalized linear mixed models (GLMM) to model the incidence of infection.

Results

There were 275 confirmed cases of WNv in the 2003 calendar year in Alberta. Our spatial model indicates that living in the grasslands natural region and levels of human testing are significant positive predictors of WNv; living in an urban area is a significant negative predictor.

Conclusion

Infected bird data contribute little to our model. The variability of West Nile virus incidence in Alberta may be partly confounded by the variations in the rate of testing in different parts of the province. However, variation in infection is also associated with known environmental risk factors. Our findings are consistent with existing knowledge of WNv in North America.

Résumé

Contexte

Dans cet article, nous appliquons une méthode de modélisation de la variation spatiale du virus du Nil occidental (VNO) chez les humains à l’aide de données d’essais sur les oiseaux, l’environnement et les humains.

Méthode

Nous avons utilisé des données recueillies auprès de 503 municipalités de l’Alberta. Pour atténuer les effets de l’autocorrélation spatiale résiduelle, nous avons fait appel à des modèles linéaires généralisés mixtes (GLMM) pour modéliser l’incidence de l’infection.

Résultats

Il y a eu 275 cas confirmés de VNO en Alberta au cours de l’année civile 2003. Notre modèle spatial montre que le fait de vivre dans la région naturelle des prairies et l’envergure des essais sur les humains sont d’importants prédicteurs positifs du VNO; le fait de vivre en milieu urbain est quant à lui un important prédicteur négatif.

Conclusion

Les données sur les oiseaux infectés jouent peu dans notre modèle. L’envergure variable des essais à différents endroits de la province pourrait être un facteur confusionnel dans la variabilité de l’incidence du virus du Nil occidental en Alberta. Cependant, les écarts dans les taux d’infection sont aussi associés à des facteurs de risque environnementaux connus. Nos constatations sont compatibles avec les connaissances actuelles sur le VNO en Amérique du Nord.

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Author information

Authors and Affiliations

  1. Department of Earth and Atmospheric Sciences, University of Alberta, 1–26 Earth Sciences Building, Edmonton, AB, T6G 2E3, Canada

    Nikolaos W. Yiannakoulias MA

  2. Public Health Surveillance and Environmental Health, Alberta Health and Wellness, Edmonton, Canada

    Nikolaos W. Yiannakoulias MA, Donald P. Schopflocher PhD & Lawrence W. Svenson BSc

  3. Department of Public Health Sciences, University of Alberta, Canada

    Donald P. Schopflocher PhD & Lawrence W. Svenson BSc

  4. Department of Community Health Sciences, University of Calgary, Calgary, AB, Canada

    Donald P. Schopflocher PhD & Lawrence W. Svenson BSc

Authors
  1. Nikolaos W. Yiannakoulias MA
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  2. Donald P. Schopflocher PhD
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  3. Lawrence W. Svenson BSc
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Correspondence to Nikolaos W. Yiannakoulias MA.

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Yiannakoulias, N.W., Schopflocher, D.P. & Svenson, L.W. Modelling Geographic Variations in West Nile Virus. Can J Public Health 97, 374–378 (2006). https://doi.org/10.1007/BF03405345

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  • DOI: https://doi.org/10.1007/BF03405345

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