West nile virus prevalence across landscapes is mediated by local effects of agriculture on vector and host communities.
Authors: Crowder David W, Dykstra Elizabeth A, Brauner Jo Marie, Duffy Anne, Reed Caitlin, Martin Emily, Peterson Wade, Carrière Yves, Dutilleul Pierre, Owen Jeb P
Journal: PloS one
Summary
# West Nile Virus Risk and Agricultural Landscapes: Implications for Equine Health West Nile virus remains a significant threat to equine populations worldwide, yet the landscape-level factors driving local transmission hotspots have remained poorly understood. Crowder and colleagues employed spatially-explicit modelling across multiple scales to investigate how three land-use categories (orchards, vegetable/forage crops, and natural habitat) and climatic variables shape WNV prevalence in mosquito vectors, avian reservoirs, and equine hosts. Orchard environments emerged as particularly problematic, increasing both local mosquito infection rates and populations of key reservoir species (American robins and house sparrows), which subsequently amplified WNV transmission at broader landscape scales—particularly when precipitation was low and temperatures favourable. Lower precipitation paradoxically correlated with reduced infections, possibly due to unfavourable breeding conditions or altered vector behaviour, though this relationship warrants further investigation. For equine practitioners operating in agricultural regions, these findings suggest that proximity to intensive orchard operations may elevate WNV risk and warrant heightened surveillance, vector control measures, and vaccination protocols; conversely, vegetable and forage crop areas presented lower transmission risk, offering a useful consideration when assessing pasture management and facility siting decisions to minimise arboviral exposure.
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Practical Takeaways
- •Horses located near orchard regions have higher WNV infection risk; increased surveillance and vaccination programs should be prioritized in these areas
- •WNV prevalence varies by agricultural landscape type and precipitation patterns; farm location relative to orchard habitats influences disease risk
- •Understanding local ecological factors (habitat type, weather patterns) helps predict WNV outbreak risk and guide preventive management strategies on individual operations
Key Findings
- •Orchard habitats were associated with greater prevalence of WNV infections in bird reservoirs and horses at landscape scales
- •Increased precipitation was associated with fewer WNV infections across landscapes
- •Orchard habitats locally increased WNV prevalence in mosquito vectors and abundance of American robins and house sparrows
- •Orchard habitats create focal transmission points for WNV at landscape scales when climatic conditions are suitable