Flying-fox roost disturbance and Hendra virus spillover risk.
Authors: Edson Daniel, Field Hume, McMichael Lee, Jordan David, Kung Nina, Mayer David, Smith Craig
Journal: PloS one
Summary
# Editorial Summary: Flying-fox roost disturbance and Hendra virus spillover risk Hendra virus poses a significant zoonotic threat to horses and humans in Australia, with Pteropus flying-foxes serving as the natural reservoir; urban roost expansion has prompted calls for dispersal programmes, yet the hypothesis that disturbance-induced stress might paradoxically increase viral shedding and spillover risk remained largely untested. Daniel and colleagues measured Hendra virus prevalence and urinary cortisol concentrations (a physiological stress marker) in flying-fox populations before, during, and after roost modification activities, analysing their data using generalised linear mixed models. Whilst HeV prevalence remained relatively stable across all periods (4.9% before, 4.7% during, 3.4% after disturbance; P = 0.440) and cortisol concentrations showed no significant overall change (P = 0.550), the researchers identified important contextual factors: cortisol levels were influenced by season and geographic region, and a small but positive association existed between active viral excretion and elevated cortisol, suggesting stress may have selective effects on shedding dynamics in susceptible individuals. The study provides reassurance that well-managed roost dispersal does not trigger a broad stress-mediated increase in population-level viral transmission, though the variation by region and the nature of disturbance activity underscores the importance of evidence-based, timing-sensitive protocols when implementing control measures.
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Practical Takeaways
- •Urban flying-fox roost dispersal and modification do not appear to significantly increase Hendra virus infection or transmission risk based on stress markers and viral prevalence
- •The nature, timing, and location of roost management activities influence flying-fox stress responses; adopting standardized best-practice protocols can minimize distress during necessary dispersal
- •Horse owners and managers in areas with flying-fox populations should focus on other biosecurity measures rather than assuming roost disturbance dramatically increases local spillover risk
Key Findings
- •HeV prevalence was similar before (4.9%), during (4.7%), and after (3.4%) roost disturbance with no significant difference (P = 0.440)
- •Urinary cortisol concentrations showed no significant change across roost disturbance phases (P = 0.550), though regional variation was noted
- •A small positive statistical association was found between HeV excretion status and urinary cortisol concentration
- •Roost disturbance effects on stress response varied by region and timing, indicating the importance of 'best practice' dispersal protocols