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Although not as well known outside of Australia as its more famous cousin - Nipah - we've covered the Hendra virus (HeV) a number of times over the years in this blog (see here, here, and here). While both are members of the family Paramyxoviridae, genus Henipavirus, only 7 human infections have been documented with Hendra.
Like all viruses, both have the potential to mutate and evolve - and over time - become better adapted to their hosts.
The Australian Department of Environment describes how Hendra is spread. `Flying foxes' is a colloquial term for Fruit bats, members of the Pteropodidae family of bats.
Flying-foxes are natural 'hosts' of Hendra virus, meaning that they carry the virus but it has little effect on them. There is no evidence to suggest they can directly transfer the virus to humans. It is believed that the virus may be transmitted from Flying-foxes to horses, via exposure to urine or birthing fluids, although this has not been confirmed. On rare occasions, humans have contracted the virus through close contact with infected horses.
And just three weeks ago Australian researchers, via a preprint article, announced the detection of a new variant of the Hendra virus. A variant that eluded existing tests for the Hendra virus.
Novel Hendra virus variant detected by sentinel surveillance of Australian horses
Edward J. Annand, Bethany A. Horsburgh, Kai Xu, Peter A. Reid, Ben Poole, Maximillian C. de Kantzow, Nicole Brown, Alison Tweedie, Michelle Michie, John D. Grewar, Anne E. Jackson, Nagendrakumar B. Singanallur, Karren M. Plain, Karan Kim, Mary Tachedjian, Brenda van der Heide, Sandra Crameri, David T. Williams, Cristy Secombe, Eric D. Laing, Spencer Sterling, Lianying Yan, Louise Jackson, Cheryl Jones, Raina K. Plowright, Alison J. Peel, Andrew C. Breed, Ibrahim Diallo, Navneet K. Dhand, Philip N. Britton, Christopher C. Broder, Ina Smith, John-Sebastian Eden
doi: https://doi.org/10.1101/2021.07.16.452724A novel Hendra virus (HeV) variant, not detected by routine testing, was identified and isolated from a Queensland horse that suffered acute, fatal disease consistent with HeV infection. Whole genome sequencing and phylogenetic analysis demonstrated the variant to have ~83% nucleotide identity to the prototype HeV strain. An updated RT-qPCR assay was designed for routine HeV surveillance. In silico and in vitro comparison of the receptor-binding protein with prototypic HeV showed that the human monoclonal antibody m102.4 used for post-exposure prophylaxis, as well as the current equine vaccine, should be effective against this variant. Genetic similarity of this virus to sequences detected from grey-headed flying-foxes suggests the variant circulates at-least in this species. Studies determining infection kinetics, pathogenicity, reservoir-species associations, viral–host co-evolution and spillover dynamics for this virus are urgently needed. Surveillance and biosecurity practices should be updated to appreciate HeV spillover risk across all regions frequented by flying foxes.
Two days ago, a horse was found infected with this novel Hendra Variant in Newcastle, New South Wales This from Australia's Department of Primary Industries.
Hendra variant case confirmed near Newcastle
8 Oct 2021
A variant Hendra virus strain has been confirmed in a 7-year-old unvaccinated Clydesdale from West Wallsend, near Newcastle.
The detection of the virus was confirmed through testing at NSW Department of Primary Industries’ (DPI) Elizabeth Macarthur Agricultural Institute laboratory and at the Australian Centre for Disease Preparedness.
DPI has routinely tested all Hendra submissions over the past 6 months for the variant Hendra strain following a retrospective detection by researchers in a Queensland horse.
A private vet attended the affected horse in response to a report that the animal was showing neurological signs, collected samples for testing and notified DPI. The affected horse was euthanised.
No other horses on the property are showing any signs of ill health.
A District Veterinarian from Hunter Local Land Services has issued an Individual Biosecurity Direction to control the movement of animals and people on and off the property for 21 days.
Public health officers from Hunter region are undertaking risk assessments of any people who have had contact with the infected horse.
Most Hendra cases in NSW have been on the north coast, with a case at Scone in 2019 being the most southern case. Vaccination of horses is the most effective way to help manage Hendra virus disease.
There have been 24 horse deaths in NSW as a result of Hendra virus on 23 properties since the first case in 2006. There have been no human deaths from Hendra virus in NSW.
Hendra virus infection is notifiable in NSW under the NSW Biosecurity Act.
Signs of infection are non-specific in the early stages and anyone who is concerned about possible Hendra infection should isolate the horse and seek veterinary advice.
If a private vet is unavailable and the illness is progressing rapidly, call the Emergency Animal Disease Hotline on 1800 675 888.
Joint media release: Researchers develop test for new Hendra variant
9 October 2021
Minister for Agriculture and Northern Australia, the Hon David Littleproud MP
Minister for Science and Technology, the Hon Melissa Price MPA newly identified Hendra virus variant has been confirmed in a horse from West Wallsend near Newcastle.
- New Hendra virus variant (HeV) confirmed in routine surveillance in New South Wales
- Researchers recently discovered this new Hendra virus variant in historical samples
- New test available nationally to identify Hendra virus variant
Minister for Agriculture and Northern Australia David Littleproud said the variant had first been found by researchers supported by $359,600 in Australian Government funding through the Biosecurity Innovation Program.
“Researchers from CSIRO and the University of Sydney investigated laboratory samples from horses which were previously suspected of having Hendra virus but had all tested negative,” Minister Littleproud said.
“They found evidence of a novel virus, later confirmed as a new variant and have now developed a diagnostic tool specific to detect it.
“The research and now this detection highlights that the geographic distribution of Hendra virus-carrying bats is likely much greater than once thought.
“Fortunately, this does not change our animal health status but it does remind us of the importance of continued investment in surveillance and science for our biosecurity system.
“Our annual $8.6 million diagnostics, preparedness and response investment in CSIRO’s Australian Centre for Disease Preparedness puts us in a very strong position to detect and respond to new and emerging animal diseases.
“We invest in vital research to provide cutting-edge scientific evidence to underpin our biosecurity.
“This includes Hendra virus testing like this, which is aimed at protecting horses and preventing spill-over of infection into humans.”
Minister for Science and Technology Melissa Price said the new test would significantly reduce infection risks for veterinarians and frontline equine workers.
“This new test shows the practical application of this research and the science that underpins it, which could save lives,” Minister Price said.
“Horses that may have tested negative under previous tests can now be confirmed as positive Hendra cases, which allows the risk to be managed through use of personal protection equipment and appropriate biosecurity practices.
“Horse owners will need to continue prudent risk management to minimise the potential for contact between all flying-foxes and horses, and to vaccinate their horses against Hendra virus.”
Minister Littleproud said, through Wildlife Health Australia, the government is bolstering wildlife surveillance to ensure we remain a step ahead of emerging diseases.
“We have a new initiative being rolled out soon – thanks to the recent injection of funding for our biosecurity system”, Minister Littleproud said.
“This work will further expand our wildlife and feral animal surveillance so that we have early warning of new and emerging disease risks with serious industry, human health or biodiversity consequences and ensure our risk management is appropriately informed.”
You can read more about the work of the ‘Horses as Sentinels’ project here
More information about Hendra virus for vets and horse owners can be found at outbreak
Fast Facts:
- Hendra virus is a zoonotic disease naturally hosted by native flying-foxes and transmittable to horses. It can be passed on to humans from infected horses and can be fatal.
- West Wallsend case represents the first (non-historical) detection of the variant in a horse in NSW, and the southern-most Hendra detection to date.
- Since 1994, seven Australians have contracted the Hendra virus. Four died, including racehorse trainer Vic Rail and two veterinarians.
- Flying-foxes are protected species. They are critical to our environment because they pollinate our native trees and spread seeds. This is particularly important in areas regenerating after bushfires.
- Without flying foxes, we would not have our eucalypt forests, rainforests and melaleucas.
- This research has been enabled by a philanthropic donation to the University of Sydney from the Dalara Foundation and a Department of Education Skills and Employment Research Training Program scholarship.
While there is no indication at this time that this variant Hendra virus poses any greater threat to humans, or horses, than the older strains - it is a reminder than nature is never satisfied with the status quo - and continues to tinker with viruses, bacteria, and other pathogens via evolution.
Bats in particular, are of great interest to researchers into emerging infectious diseases, as they are believed hosts to dozens of zoonotic (or potentially zoonotic) pathogens.
A few recent blogs on the role of bats in carriage and spread of novel viruses include:
Nature: Coronaviruses Closely Related to the Pandemic Virus Discovered in Japan & Cambodia
PNAS: Nipah Virus Dynamics in Bats and Implications for Spillover to Humans
Curr. Opinion Virology: Viruses In Bats & Potential Spillover To Animals And Humans
