CSIRO researchers have been actively involved in Hendra virus research since it first emerged in 1994. A dangerous zoonotic virus, Hendra can spread from flying foxes to horses, and from horses to humans.
Scientists at our Australian Centre for Disease Preparedness (ACDP) isolated and identified the virus and developed diagnostic tests capable of detecting it.
Now they have found a new genetic type of Hendra virus in flying foxes in southern and western Australia, confirming Hendra can be found across a broad region of Australia.
Studying flying fox samples
Previous studies suggested the black flying fox and the spectacled flying fox were the primary carriers of Hendra virus.
However, a team of scientists have been monitoring samples collected from flying foxes each year from 2013 to 2021. By piecing together the new virus’ genome from bat samples, our researchers identified a new genetic type of the Hendra virus in grey headed flying foxes in Victoria and South Australia and the little red flying fox in Western Australia.
They have called it Hendra Virus Genotype 2 (HeV-g2).
Horses and the new type of Hendra
In another project called “Horses as Sentinels”, led by the University of Sydney and CSIRO, samples from Australian horses were studied for the presence of a range of viruses, including the new genetic type, HeV-g2.
The project, funded by a Biosecurity Innovation Program grant from the Department of Agriculture, Water and the Environment, found HeV-g2 present in samples collected from one horse from Queensland, in 2015. The horse presented with severe disease signs consistent with Hendra virus infection. Results of this research are available in preprint.
In October 2021, the new genetic type was also detected in a horse near Newcastle in New South Wales, the most southern case of Hendra yet recorded.
As HeV-g2 is genetically very similar to the original Hendra virus, which can be deadly, our researchers say there is a risk to horses in all areas where flying foxes are found in Australia.
If you are concerned about a sick horse, please isolate the horse away from other horses and people and contact your vet for advice.
More information about Hendra virus for vets and horse owners can be found at Outbreak, a website hosted and managed by the Department of Agriculture, Water and the Environment, which provides information about emergency animal, plant pest and disease incursions affecting Australia.
New diagnostic tests
CSIRO and the “Horses as Sentinels” project team have been working closely with vets and laboratories around Australia to implement improved tests for horses with signs of Hendra virus disease. The tests can detect and differentiate both types of Hendra virus with a high degree of accuracy.
Does the current vaccine work?
While further research is needed, researchers expect the current Hendra virus vaccine will also work against the new Hendra virus variant.
Flying foxes and horses
This finding is a reminder of measures that horse owners and people who work closely with horses can put in place to reduce the risk of infection.
Biosecurity measures, such as vaccination of horses for Hendra virus and seeking veterinary attention for sick horses will help to minimise the risk of disease transmission.
To help prevent Hendra virus in horses, reduce the opportunity for flying-foxes and horses to interact. Do this by removing feed bins and water troughs from under or near trees. Remove horses or restrict their access to paddocks where flowering or fruiting trees attract flying-foxes.
Flying foxes are protected animals, with two species on our nationally vulnerable list. They are critical to our environment because they pollinate our native trees and plants and also spread their seeds.
Without flying foxes, we wouldn't have our eucalypt forests, rainforests and melaleucas.