Permissive summer temperatures of the 2010 European West Nile fever upsurge.
Authors: Paz Shlomit, Malkinson Dan, Green Manfred S, Tsioni Gil, Papa Anna, Danis Kostas, Sirbu Anca, Ceianu Cornelia, Katalin Krisztalovics, Ferenczi Emőke, Zeller Herve, Semenza Jan C
Journal: PloS one
Summary
# Editorial Summary: West Nile Fever and European Summer Temperatures West Nile Fever (WNF) caused significant human illness across Europe during summer 2010, with preceding heat waves suggesting a potential climate link; this study investigated whether spring and summer temperature patterns, humidity, and rainfall could predict outbreak timing and severity. Using statistical correlation and logistic regression analysis across multiple European countries with varying climates, researchers examined the relationship between meteorological conditions and both human and equine disease cases. Temperature emerged as the strongest predictor of human WNF cases, though with notable geographic variation: northern European countries showed robust correlations with a lag of up to four weeks between temperature spikes and illness peaks, whilst southern countries experienced immediate responses, suggesting different vector amplification rates at different latitudes. Equine morbidity lagged three weeks behind human cases where comprehensive surveillance data existed, but showed no significant associations with temperature or humidity during the four-week observation window. For equine professionals and veterinarians working in temperate climates, these findings suggest that sustained periods of above-average summer temperatures warrant heightened vigilance for WNF emergence, particularly given the three-week delay between human and horse cases—allowing a potential window for vector control interventions before equine populations are affected.
Read the full abstract on PubMed
Practical Takeaways
- •Monitor for potential WNF outbreaks in horses during and following sustained heat spells, with higher vigilance in northern European regions
- •Horse disease typically emerges 3 weeks after human cases—establish surveillance protocols that detect human cases early to enable preventive vector control
- •Temperature is a more reliable environmental precursor than humidity or rainfall for predicting WNF risk in equine populations
Key Findings
- •Positive correlation between summer temperatures and human WNF cases, with stronger effects in northern Europe (up to 4-week lag) versus immediate response in southern Europe
- •Horse morbidity lagged 3 weeks behind human cases where integrated surveillance was conducted
- •No significant associations found between temperature or relative humidity and horse morbidity at 0-4 week lags
- •Relative humidity showed weaker correlations with WNF outbreaks; precipitation associations were inconsistent