Routes of Hendra Virus Excretion in Naturally-Infected Flying-Foxes: Implications for Viral Transmission and Spillover Risk.
Authors: Edson Daniel, Field Hume, McMichael Lee, Vidgen Miranda, Goldspink Lauren, Broos Alice, Melville Deb, Kristoffersen Joanna, de Jong Carol, McLaughlin Amanda, Davis Rodney, Kung Nina, Jordan David, Kirkland Peter, Smith Craig
Journal: PloS one
Summary
# Editorial Summary: Hendra Virus Excretion Routes in Flying-Foxes Hendra virus poses a genuine spillover risk to horses and handlers in eastern Australia, yet until recently the relative importance of different excretion routes in naturally infected bats remained unclear. Daniel and colleagues conducted an extensive field study between 2012 and 2014, sampling 2,840 flying-foxes across three species from Queensland and New South Wales using a sensitive qRT-PCR assay to detect viral RNA in urine, serum, faecal, nasal, oral and urogenital samples. Among the 1,410 *Pteropus alecto* sampled, 42 individuals (1.76% of all samples) tested positive, with urine yielding substantially higher viral loads than serum, faecal, nasal or oral samples, whilst critically, neither *P. poliocephalus* nor *P. scapulatus* showed any detectable virus. These findings provide robust epidemiological evidence that urine represents the primary transmission route in naturally infected bats and the most likely source of equine exposure at the bat-horse interface—a distinction with direct implications for targeted risk mitigation strategies on properties where *P. alecto* populations congregate near horse facilities. For practitioners managing at-risk properties, this research emphasises the importance of reducing horses' contact with bat urine through management of water troughs, feed sources and shelter areas near known bat roosts, and reinforces that species-specific risk profiles should inform herd health protocols in endemic regions.
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Practical Takeaways
- •Focus Hendra virus prevention measures on minimising horse exposure to flying-fox urine rather than other bodily secretions—this identifies the highest-risk contamination source at the bat-horse interface
- •Recognise that P. alecto (black flying-fox) poses the primary spillover risk; other Australian species show negligible infection dynamics and are unlikely sources of equine infection
- •Use urine collection as the preferred diagnostic sample if testing flying-foxes for Hendra virus surveillance, as it has superior sensitivity to other sample types
Key Findings
- •Urine was the primary route of Hendra virus excretion in naturally infected flying-foxes, with detection rates substantially higher than serum, faeces, nasal, and oral secretions
- •Only Pteropus alecto showed detectable HeV RNA (1.76% overall detection rate; 42/1410 animals), while P. poliocephalus and P. scapulatus showed no detections despite large sample sizes (n=1430 animals combined)
- •Urine sampling was more efficient for HeV detection than urogenital swabs, and HeV RNA detection in serum suggests haematogenous spread and potential latency/recrudesence in the host
- •Findings provide evidence to target equine risk mitigation strategies toward preventing exposure to bat urine rather than other secretion routes