title: Permissive summer temperatures of the 2010 European West Nile fever upsurge.
abstract: BACKGROUND
  In the summer of 2010, Europe experienced outbreaks of West Nile Fever (WNF) in humans, which was preceded by hot spells. The objective of this study was to identify potential drivers of these outbreaks, such as spring and summer temperatures, relative humidity (RH), and precipitation.
  
  
  METHODS
  Pearson and lag correlations, binary and multinomial logistic regressions were used to assess the relationship between the climatic parameters and these outbreaks.
  
  
  RESULTS
  For human morbidity, significant (<0.05) positive correlations were observed between a number of WNF cases and temperature, with a geographic latitude gradient: northern ("colder") countries displayed strong correlations with a lag of up to four weeks, in contrast to southern ("warmer") countries, where the response was immediate. The correlations with RH were weaker, while the association with precipitation was not consistent. Horse morbidity started three weeks later than in humans where integrated surveillance was conducted, and no significant associations with temperature or RH were found for lags of 0 to 4 weeks.
  
  
  CONCLUSIONS
  Significant temperature deviations during summer months might be considered environmental precursors of WNF outbreaks in humans, particularly at more northern latitudes. These insights can guide vector abatement strategies by health practitioners in areas at risk for persistent transmission cycles.
authors: Department of Geography and Environmental Studies, University of Haifa, Haifa, Israel.
authors: Shlomit
authors: S
authors: Paz
authors: Dan
authors: D
authors: Malkinson
authors: Manfred S
authors: MS
authors: Green
authors: Gil
authors: G
authors: Tsioni
authors: Anna
authors: A
authors: Papa
authors: Kostas
authors: K
authors: Danis
authors: Anca
authors: A
authors: Sirbu
authors: Cornelia
authors: C
authors: Ceianu
authors: Krisztalovics
authors: K
authors: Katalin
authors: Emőke
authors: E
authors: Ferenczi
authors: Herve
authors: H
authors: Zeller
authors: Jan C
authors: JC
authors: Semenza
mesh_terms: D025041:Animal Migration; D000818:Animals; D004196:Disease Outbreaks; D005060:Europe / Q000453:epidemiology; D006734:Horse Diseases / Q000453:epidemiology* / Q000821:virology; D006736:Horses; D006801:Humans; D015994:Incidence; D012621:Seasons; D014901:West Nile Fever / Q000453:epidemiology / Q000662:veterinary*