Environmental predictors of West Nile fever risk in Europe

Annelise Tran, Bertrand Sudre, Shlomit Paz, Massimiliano Rossi, Annie Desbrosse, Véronique Chevalier, Jan C. Semenza

Research output: Contribution to journalArticlepeer-review


West Nile virus (WNV) is a mosquito-borne pathogen of global public health importance. Transmission of WNV is determined by abiotic and biotic factors. The objective of this study was to examine environmental variables as predictors of WNV risk in Europe and neighboring countries, considering the anomalies of remotely sensed water and vegetation indices and of temperature at the locations of West Nile fever (WNF) outbreaks reported in humans between 2002 and 2013.Methods: The status of infection by WNV in relationship to environmental and climatic risk factors was analyzed at the district level using logistic regression models. Temperature, remotely sensed Normalized Difference Vegetation Index (NDVI) and Modified Normalized Difference Water Index (MNDWI) anomalies, as well as population, birds' migratory routes, and presence of wetlands were considered as explanatory variables.Results: The anomalies of temperature in July, of MNDWI in early June, the presence of wetlands, the location under migratory routes, and the occurrence of a WNF outbreak the previous year were identified as risk factors. The best statistical model according to the Akaike Information Criterion was used to map WNF risk areas in 2012 and 2013. Model validations showed a good level of prediction: area under Receiver Operator Characteristic curve = 0.854 (95% Confidence Interval 0.850-0.856) for internal validation and 0.819 (95% Confidence Interval 0.814-0.823) (2012) and 0.853 (95% Confidence Interval 0.850-0.855) (2013) for external validations, respectively.Conclusions: WNF incidence is increasing in Europe and WNV is expanding into new areas where it had never been observed before. Our model can be used to direct surveillance activities and public health interventions for the upcoming WNF season.

Original languageEnglish
Article number26
Number of pages11
JournalInternational Journal of Health Geographics
StatePublished - 1 Jul 2014

Bibliographical note

Funding Information:
This study was financed by ECDC (OJ/2012/02/16 – PROC/2012/015). We are grateful to the support from G. Balança, N. Gaidet, M. Gely, T. Baldet, and T. Balenghien from CIRAD, J. Figuerola from Estación Biológica Doñana, CSIC, L. Marrama, and A. Donachie from ECDC, and Pshem Busse from the Eastern European bird migration network for migration flyways information.


  • Arbovirus
  • Environmental determinants
  • Epidemiology
  • Remote sensing
  • Risk maps
  • Surveillance
  • Temperature
  • West nile fever
  • West nile virus

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • General Business, Management and Accounting
  • General Computer Science


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