Physiological stress and Hendra virus in flying-foxes (Pteropus spp.), Australia.
Authors: McMichael Lee, Edson Daniel, Smith Craig, Mayer David, Smith Ina, Kopp Steven, Meers Joanne, Field Hume
Journal: PloS one
Summary
# Editorial Summary: Physiological Stress and Hendra Virus in Flying-Foxes Flying-foxes (Pteropus species) serve as the natural reservoir for Hendra virus, a paramyxovirus capable of causing fatal infections in horses and humans across Australia, yet the mechanisms triggering viral shedding in bat populations remain poorly understood. McMichael and colleagues investigated whether physiological stress—measured via urinary cortisol concentrations—correlates with Hendra virus excretion in wild Australian flying-fox colonies across two geographically distinct Queensland regions, using non-invasive urine sampling combined with PCR-based viral detection and enzyme immunoassay for cortisol quantification. Whilst no direct relationship emerged between elevated cortisol and active viral shedding, the researchers identified a biologically plausible indirect pathway: lower winter temperatures were associated with increased urinary cortisol in Black flying-foxes (P. alecto), suggesting that thermogenic stress may indirectly promote Hendra virus infection and excretion through metabolic demand rather than via direct immune suppression. This finding carries important implications for equine practitioners and animal health professionals managing Hendra risk, indicating that seasonal temperature fluctuations—particularly in southeastern Queensland—may predict periods of heightened viral circulation in bat populations and consequently elevated spillover risk to horse populations. The non-invasive sampling methodology and disease ecology framework presented here establish a template for investigating emerging henipaviruses and other zoonotic pathogens at the wildlife–livestock interface.
Read the full abstract on PubMed
Practical Takeaways
- •Hendra virus risk in horses may increase during winter months in Australian regions due to stress-mediated immunosuppression in flying-fox reservoirs, not direct temperature effects
- •Biosecurity protocols for horse facilities should account for seasonal Hendra virus dynamics linked to bat physiological stress rather than virus presence alone
- •Understanding disease ecology at the wildlife-livestock interface requires multi-factorial investigation beyond direct pathogen-stress correlations
Key Findings
- •No direct correlation found between urinary cortisol levels and Hendra virus excretion in flying-fox populations
- •Low winter temperatures associated with elevated cortisol in Pteropus alecto in Southeast Queensland roosts
- •Indirect association hypothesized between low winter temperatures and increased Hendra virus infection mediated by thermoregulation costs
- •Non-invasive pooled and individual urine sampling successfully detected Hendra virus and measured stress biomarkers in wild flying-fox populations