Spatial and temporal distribution of West Nile virus in horses in Israel (1997-2013)--from endemic to epidemics.
Authors: Aharonson-Raz Karin, Lichter-Peled Anat, Tal Shlomit, Gelman Boris, Cohen Daniel, Klement Eyal, Steinman Amir
Journal: PloS one
Summary
# Editorial Summary: West Nile Virus Epidemiology in Israeli Horse Populations Between 1997 and 2013, researchers conducted serological surveys across Israeli horse populations to track West Nile virus (WNV) exposure and identify environmental factors driving the shift from endemic circulation to epidemic outbreaks, particularly following the devastating 2000 human and equine outbreak. Serum samples from horses collected at three timepoints revealed dramatic increases in WNV seroprevalence: 39% in 1997, 66.1% in 2002, and 85.5% in 2013, with horses residing along the Great Rift Valley—a major migratory flyway for birds—showing consistently elevated infection rates compared to other regions. The analysis identified age and breed as demographic risk factors for seropositivity, whilst environmental data indicated that reduced spring rainfall during 1997–2007 correlated with heightened human disease incidence, suggesting meteorological stress may amplify virus transmission cycles. The findings propose that Israel contains two distinct epidemiological zones: a persistently endemic region along the birds' migration corridor where WNV remains established, and the remainder of the country experiencing periodic epidemic waves potentially triggered by drought conditions affecting vector populations and bird movements. For equine professionals, this work underscores the importance of geographical risk assessment when advising on WNV exposure, disease prevention strategies, and the value of monitoring seasonal weather patterns as potential predictors of increased outbreak risk in your region.
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Practical Takeaways
- •Horses in migration corridor regions (like the Great Rift Valley in Israel) face endemic WNV exposure year-round; serological monitoring and biosecurity planning should account for this persistent threat.
- •Seasonal patterns linked to spring precipitation suggest WNV risk management strategies should intensify during drought periods, when epidemic potential appears to increase.
- •Age and breed differences in susceptibility may warrant targeted prevention strategies; consult herd management plans with regional epidemiological data in mind.
Key Findings
- •WNV seroprevalence in Israeli horses increased from 39% (1997) to 66.1% (2002) to 85.5% (2013), indicating transition from endemic to epidemic state.
- •Horses along the Great Rift Valley (major bird migration route) showed persistently and significantly higher seroprevalence than other regions.
- •Age and breed were identified as demographic risk factors for WNV infection in horses.
- •Spring drought conditions were associated with increased human WNV incidence and potential transition from endemic to epidemic phases.