Flying-fox species density--a spatial risk factor for Hendra virus infection in horses in eastern Australia.
Authors: Smith Craig, Skelly Chris, Kung Nina, Roberts Billie, Field Hume
Journal: PloS one
Summary
# Editorial Summary: Flying-Fox Density as a Spatial Risk Factor for Equine Hendra Virus Infection Hendra virus remains a significant threat to Australian horses and the humans in contact with them, with flying-foxes (Pteropus species) serving as the natural reservoir; understanding the spatial distribution of infection risk is therefore critical for targeted prevention strategies. Researchers employed sophisticated spatial analysis techniques—including Global Moran's I autocorrelation analysis, Getis-Ord hot-spot mapping, and geographically weighted regression—to examine equine Hendra cases across eastern Australia and identify environmental and biological correlates of infection risk. Flying-fox density, particularly of *Pteropus alecto* and *P. conspicillatus*, emerged as the strongest predictor of equine case clustering, with significant infection hot spots identified along the Queensland–New South Wales coast spanning up to 300 km, suggesting that proximity to and density of these specific bat species drives localised transmission risk more reliably than horse density, climate, or vegetation patterns. Notably, case clustering occurred at 40 km intervals consistent with known flying-fox foraging ranges, providing spatial validation for the epidemiological hypothesis. Practitioners should consider their proximity to known *P. alecto* and *P. conspicillatus* roosts when assessing individual property risk and implementing biosecurity measures, though the GWR residuals indicate that property-level factors beyond species density—such as management practices or specific environmental features—likely modulate transmission risk and warrant further investigation.
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Practical Takeaways
- •Properties within 40 km of flying-fox roosts, particularly those near P. alecto and P. conspicillatus colonies, face elevated Hendra virus risk—prioritise biosecurity and vaccination in these high-risk zones
- •Geographic location along the eastern coastal corridor (QLD-NSW border region) represents a critical risk zone; standard preventive measures should be enhanced in these hotspot areas
- •Property-level risk factors beyond flying-fox density remain unidentified; work with local vets to assess individual property characteristics that may increase exposure risk
Key Findings
- •Significant spatial clustering of equine Hendra virus cases occurred at 40 km distances, consistent with flying-fox foraging range
- •Flying-fox species P. alecto and P. conspicillatus density showed strongest positive correlation with equine infection cases
- •Multiple infection hotspots identified along eastern Australian coast spanning 300 km from southern Queensland to northern New South Wales
- •Horse density, climate variables, and vegetation variables were not significant risk factors for equine infection