Hendra virus – Biosecurity advisory
Date of issue: 14 October 2021
Hendra virus – further genotype detected in Victorian flying foxes
Researchers from CSIRO’s Australian Centre for Disease Preparedness (ACDP) have identified a further genotype of Hendra virus in samples collected from Australian flying foxes. This confirms the longstanding knowledge that Australian flying fox species are the natural host for Hendra viruses.
The same virus was last week detected in a horse near Newcastle in New South Wales (NSW) – the most southern detection of Hendra virus in a horse to date. This follows on from a detection earlier this year, in an historic sample from a Queensland horse. These detections suggest the virus is pathogenic to horses and could also pose a zoonotic threat to people. As our knowledge increases the assessment of risk may change, but currently remains unchanged.
The ACDP study examined archived samples from 98 flying foxes – dating back to 2013. Researchers found the virus in 11 flying foxes, including seven grey-headed flying foxes from Victoria. Based on phylogenetic analysis, the genome was designated Hendra virus genotype 2 (HeV-g2).
Features of HeV-g2 suggest that it has similar epidemiology, host predilection and clinical outcomes of the already known Hendra virus. The finding alone therefore does not change the risk associated with Hendra viruses in Australia/Victoria but confirms that Hendra can be found in flying foxes broadly across Australia.
Flying foxes have never been shown to transmit Hendra virus directly to humans, therefore there is no change to the public health risk associated with handling of flying foxes. People handling flying foxes should remain aware of the risk of other bat-borne diseases. They should be trained in safe handling, vaccinated against Australian bat lyssavirus, and wear personal protective equipment.
People can be infected with Hendra virus through contact with infected horses. Though spillover of Hendra virus to horses has not occurred in Victoria, these findings remind us that Victoria is not risk-free and precautions should be taken. This is of particular importance in areas where there are large flying fox populations and with horses arriving from Queensland or NSW.
A highly effective Hendra vaccine is available for horses. ACDP studies have shown that serum from vaccinated horses can neutralise the new genotype suggesting that the vaccine is effective against HeV-g2.
The risks can also be minimised by:
- removing horse feed and water containers from under trees where flying foxes may be roosting or feeding
- early isolation of a sick horse while awaiting veterinary attention
- good hygiene and cleaning practices
- isolate new horses to your property. Carefully monitor their health and report any signs of illness early.
People should always adopt caution when a horse is unwell. Avoid contact with a sick horse that is showing clinical signs when Hendra virus is a possible diagnosis. Strict infection control measures should be implemented, noting that minimum level of PPE for airborne precautions includes a properly fitted disposable P2 respirator.
The finding of HeV-g2 has implications for laboratory testing of suspected cases of Hendra virus in horses, as extended screening is needed is to detect the virus. In Victoria, all Hendra virus exclusion testing is performed at ACDP using extended screening. As such, Agriculture Victoria advises that the Hendra exclusion testing being performed in Victoria is capable of detecting both known Hendra genotypes.
Horse owners and veterinarians are reminded to remain vigilant for diseases such as Hendra and should report any unusual illness or suspicion of disease to the Emergency Animal Disease Watch Hotline on 1800 675 888.
Further information about investigating suspect cases of Hendra: