Spatio-Temporal Identification of Areas Suitable for West Nile Disease in the Mediterranean Basin and Central Europe

PLoS One. 2015 Dec 30;10(12):e0146024. doi: 10.1371/journal.pone.0146024. eCollection 2015.

Abstract

West Nile virus (WNV) is a mosquito-transmitted Flavivirus belonging to the Japanese encephalitis antigenic complex of the Flaviviridae family. Its spread in the Mediterranean basin and the Balkans poses a significant risk to human health and forces public health officials to constantly monitor the virus transmission to ensure prompt application of preventive measures. In this context, predictive tools indicating the areas and periods at major risk of WNV transmission are of paramount importance. Spatial analysis approaches, which use environmental and climatic variables to find suitable habitats for WNV spread, can enhance predictive techniques. Using the Mahalanobis Distance statistic, areas ecologically most suitable for sustaining WNV transmission were identified in the Mediterranean basin and Central Europe. About 270 human and equine clinical cases notified in Italy, Greece, Portugal, Morocco, and Tunisia, between 2008 and 2012, have been considered. The environmental variables included in the model were altitude, slope, night time Land Surface Temperature, Normalized Difference Vegetation Index, Enhanced Vegetation Index, and daily temperature range. Seasonality of mosquito population has been modelled and included in the analyses to produce monthly maps of suitable areas for West Nile Disease. Between May and July, the most suitable areas are located in Tunisia, Libya, Egypt, and North Cyprus. Summer/Autumn months, particularly between August and October, characterize the suitability in Italy, France, Spain, the Balkan countries, Morocco, North Tunisia, the Mediterranean coast of Africa, and the Middle East. The persistence of suitable conditions in December is confined to the coastal areas of Morocco, Tunisia, Libya, Egypt, and Israel.

MeSH terms

  • Animals
  • Climate
  • Environment
  • Europe / epidemiology
  • Horse Diseases / epidemiology
  • Horse Diseases / virology
  • Horses / virology
  • Humans
  • Mediterranean Region / epidemiology
  • Spatio-Temporal Analysis
  • West Nile Fever / epidemiology*
  • West Nile Fever / transmission
  • West Nile Fever / veterinary
  • West Nile virus / physiology

Grants and funding

The authors received no specific funding for this work. Abdennasser Benjelloun performed laboratory tests at the laboratories of Société de Produits Biologiques et Pharmaceutiques vétérinaires (Biopharma), during his period of PhD. Mehdi El Harrak is employed by Société de Produits Biologiques et Pharmaceutiques vétérinaires (Biopharma), which is a semi-public company financed in large part by Ministry of Agriculture. Société de Produits Biologiques et Pharmaceutiques vétérinaires (Biopharma) provided support in the form of a salary for author MEH and for research materials. Société de Produits Biologiques et Pharmaceutiques vétérinaires (Biopharma) did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific role of these authors is articulated in the ‘author contributions’ section.